First of all, there's no firmware password or anything fancy. I'm trying to diagnose a late-2011 MacBook Pro 15", and I'm trying to get into the single user mode. I press and hold Cmd+S (the left Cmd, if it changes anything) but I'm not getting into the mode. I've tried pressing (and holding) it before pressing the power button, at the same time, a little after etc. I've tried all the combinations. It just won't enter. It will keep booting or let's say (try booting) into the OS where it gets stuck. When I press Cmd+S, however, I can see a very brief terminal in the middle for a very short/split second, and it disappears as I haven't pressed it all. What am I doing wrong?  UPDATE: I've tried Cmd+S on another 15" MacBook Pro from 2011, and it behaves the same: It just won't let me into recovery mode. They are both Yosemite, one is 10.10.3, and I can't tell the other one's minor version since I can't boot into the system in any way (and it's owner doesn't know the version either).  UPDATE 2: As Buscar웃 asked me about the verbose mode process, I took a video of booting into verbose mode:   UPDATE 3: Here's a GIF version of the video. I had to reduce quality and size a lot, but you'd get the general idea:
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I've got a Late-2011 15" MacBook Pro stuck in the gray screen when booting AFTER login. I've tried removing the drive (it's non-retina) and booting from a working bootable Yosemite installer, no luck. (it sees the startup USB drive, the progress bar progresses, but stuck at the gray screen again even without a drive.  Tried NVRAM reset (cmd option P R), it has reset (the login sound's volume changed) but nothing changed.  Tried holding D on startup, AHT doesn't start, instead, it tries to boot into the OS.  Tried Cmd V, it sometimes works and displays the verbose output, sometimes, it acts like I haven't even pressed. Again, stuck after login.  Tried booting again from USB, I select USB (after seeing both drives correctly), but no luck, it's also stuck.  I've stumbled upon this:    I've tried booting into single user mode with Cmd S, it worked ONCE, I've disabled the graphics extensions just as shown at that post, restarted, but again, nothing changed.  More weirdly, now the Cmd S doesn't work either. It just takes me to login screen without showing the terminal, just as I haven't pressed anything.  Why would this happen? Why would a Mac refuse to enter hardware test mode, single user mode, or refuse to boot from a working bootable Yosemite drive both with or without the main drive installed?  UPDATE: I've run the AHT and got an error:  4MEM/66/40000000: 0x84e0ec98  It looks like a memory issue, but I'm not sure.   UPDATE 2: I've tried reinserting the RAMs and the the problem is not reported anymore. However, the Mac still won't boot.
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Something came up today that bugged me a bit, I left my laptop on battery power before going to bed. When starting it up the battery was dead. I plugged it in, and here is what happened:  The startup progress bar came up for a while and then a forgot password prompt came up, with questions like: "set a new password" + 2 other options that I can't remember (they weren't relevant) and a previous and next arrows.  Puzzled, I hit previous and the dialog froze. I proceeded to restart again and ended up on the same dialog, I reset my password to the same as my previous and that was it.  Any idea what might have happened?
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I am not happy with El Capitan, and it is also not compatible with both music hardware and software that I have, so I want to go back to Snow Leopard on my late 2009 iMac. After installing El Capitan the CD drive on my iMac is not working, and I was unable to install Snow Leopard from it.  So I made a bootable USB that gets recognized when I hold option when the machine is booting. When I choose it, I get the white screen with the Apple logo, but it doesn't go into the installation phase. I have formatted my drive and no longer have El Capitan on it.  How can I install Snow Leopard? It looks to me(and I'm hopefully wrong about this) like El Capitan has blocked the option to downgrade to an earlier OS, and it is a bit infuriating that I am not in control of hardware that I have spent a lot of money on.
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I was recently gifted an old Mid 2010 Macbook Pro with the following specs listed here:    I would like to do a few things to it, but I have never owned an apple computer before and I know there are some restrictions on the hardware i can purchase to upgrade it.  These are the things I want to do  1) Upgrade Ram: Currently it has 2x2GB of RAM in it. This model is rated for up to 8GB but I have been reading online and it seems some people have been able to successfully install 16GB of RAM, so i am confused. Does anyone have a definitive statement on whether or not this Macbook Pro will work with 16GB of RAM? If it does accept 16GB total which RAM should i buy for a Macbook Pro like this? If it only accepts 8GB total which RAM should i buy? And I know the clock speed must be 1066Hz for this Macbook Pro, but can i use DDR3, or DDR4 RAM? Does the DDR type matter?  2) Install Secondary Hard Drive: I am not 100% so i need someone to inform me but i believe there is space in this Macbook Pro for a second hard drive. Does the CD Drive need to be removed in order for a second Hard Drive to be put in? Or is there simply space inside it for a second hard drive but not installed by Apple? Either way I would like to install an SSD into it and install the Operating System onto that SSD. Which SSD can i look to buy that is compatible with this  Pro?  3) Fresh install of Mac OSX: As it currently stands my friend who gave this laptop to me didn't erase his data. I am uncomfortable with this and want a fresh start. How do I do a fresh install of Mac OSX Mavericks (or should i wait for Yosemite?). Where can i buy a Disk/USB for it (or make a disk/USB for it) to do a clean install and how do i format a Macbook Pros hard drive and install fresh? Should this be done at an apple store?  4) Higher Screen Resolution: This is my lowest priority and I don't think it is possible to do without major invasive changes to the Macbook Pro but i want to know if it is possible. Currently the Max Resolution on the Device is 1440x900, i would like to know if it is possible to replace the LCD with one that is 1920x1080 for high resolution.
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For whatever reason, one of our macs didn't make a recovery partition when it upgraded to Lion.  Is it possible to add a recovery partition after the fact?     To be clear - on a normal mac, the recovery partition is hidden in both the Startup Disk system preference and the Disk Utility. You can only see it from the command line with a direct command, diskutil list or enabling the debug menu in Disk Utility. It also shows up if you boot with the option key held or if you successfully boot to recovery with Command-R a.k.a. ⌘+R during boot.  Warning - this question and answer ONLY APPLY to 10.7.x Lion - using the Lion installer to recreate recovery on newer OS can and will cause problems due to drivers not being present for newer OS and hardware.
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When I use my laptop, I have no trouble at all accessing the BIOS and changing things like the boot order.   However I recently got an iMac and have found that not only do the usual keys not get me to the BIOS, but when I find one that gets me to a boot menu (holding option when booting up) it won't recognize my USB boot drive of Ubuntu!  How can I access the BIOS menu like I could in a PC?
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I purchased a Late-2011 MacBook Pro 15" used a month ago. At the time of purchase, I successfully ran the .  I've since installed a new SSD and aftermarket RAM. The computer appears to be functioning normally (I'm typing this post on it), but I'd like to run the full hardware test to verify everything is OK.  But I can't seem to get it to load into the hardware test.  I've tried holding down D before pressing the power button on as well as right before the grey screen comes up. I'm confused because I've done this before without any problems.  Is there something obvious I'm doing wrong or is there a way I can check for problems that would stop the AHT from starting?    Additional info by @gentmatt:  The last time I have performed the Apple Hardware Test, my MacBook Pro was running 10.7.2. As of today, I'm running 10.7.3.  The AHT loaded even after I had installed my custom SSD and RAM. But not this time.
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I had an issue with my MacBook Air "Core i5" 1.6 13" (Early 2015) (MacBookAir7,2) and after repeated problems I decided to wipe the computer and give it a clean slate.   I downloaded a copy of Mavericks and Yosemite off the internet and created a bootable external hard drive with an iMac. I've tried both Mavericks and Yosemite but always get the prohibited sign.   I tried cmd + S while booting with the hard drive and it said "This version of Mac OS X is not supported on this platform" for both versions of OS X. The funny thing is I tried the bootable hard drive with the old iMac I have in the house and it booted into the installer just fine.   What can I do to fix this issue?
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Alrighty, I have perused the threads already in existence and am finding none of them seem to have the exact combination of variables I've got going.  I'm working on a computer using Ubuntu 12.04. Currently, it boots straight into tty1  Ubuntu 12.04.4 LTS [computer name] tty1  [computer name] login: Password:   Login leads to:  Last login: Wed Mar 19 13:47:11MDT 2014 on tty1  Welcome to Ubuntu 12.04.4 LTS (GNU/Linux 3.2.0-32generic-pae i686   The owner of the computer stated that this issue happened after a recent update, if that gives anyone a hint as to the specific location of the graphics failure.   I'm capable of booting into the GUI utilizing startx, but am frankly at a loss of where to go from here. Years of Windows has molded me into a GUI heavy kinda person, so, if possible, work off the assumption that I've no idea what you're talking about and break it down to the simplest of steps.  Thanks!
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Today i format my "OS X El capitan" partition for installing "Yosemite". But due an error in bootable yosemite usb it didn't install on this partition. After some hours when i turned on iMac and hold down "option" key for boot into usb but just blank screen and mouse show. And every time when i turend on iMac it only show flashing folder with question mark. I've tried to resolve it by reseting "NVRAM". But after restarting problem still same.  Also I've tried many "Startup key combinations for Mac" but didn't work any combination on startup.  Also i have important data in my other one partition. Please can anyone tell me what i do for resolving that issue Without loosing my data?
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I would like to find out if I can set a new firmware password via Find My Mac? I already have my MacBook added but the firmware lock is active and I have no idea what it is, I've tried all combinations but they haven't worked.  If I choose to lock it using Find My Mac, will I be asked to create a new key or does that activate and expect me to enter the one it believes is already there?
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I've made a bit of a balls up...  When attempting to create a bootable Ubuntu usb drive I accidentally ran dd on my main system drive :(  sudo dd if=/path/to/image.img of=/dev/rdisk1 bs=1m   I realised what I'd done pretty quickly but everything seemed fine so I re-ran the command on the correct drive /dev/disk2 and thought "phew not sure how I got away with that"... Then things started going wrong... I could continue using the applications I had open but opening anything new / accessing the hdd caused that thing to lock.  Sadly I haven't been using time machine, lesson learnt!   I spoke to AppleCare who said I need to reformat the machine but I'm really hoping there's some way to restore whatever 1m I destroyed (I'm assuming something to do with the partition information). Wishful thinking?  Also, AppleCare told me to restart, which means I can only user repair mode utils.  Help!
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I have lately been experiencing this problem on my Mac book pro 13" mid 2010 where it usually hangs and doesn't  resume normal working. I try to restart the computer but it gets stuck at the progress bar. I have tried everything from safe mode boot, PRAM reset, disk utility first aid in recovery and time machine restoration but the problem persists until I reinstall OSX (it worked the last time at least). Now it has hit again. Need suggestions on how to deal with it. I'm using Mac OS X El Capitan and it gets stuck at approximately the 90% mark.
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So I have a 2010 15" macbook pro (MBP6,1) and I replaced the optical drive with a hard disk. I wanted to install windows 7 on the hard disk with boot camp with a USB and ISO image.  After searching I found that I need to modify my plist.info to allow my boot camp to create a bootable USB (since normally it doesn't have the option to create the USB for my model since it came with a disk drive).   After doing so and seemingly having a fine (but long) install process onto the USB. I told boot camp how much space to partition windows on and hit install.  Then the computer restarted. When it came back up it was stuck on a grey apple logo screen forever (I waited 15 minutes to ensure it wasn't just "thinking"). I force restarted and the next time it turned on it got stuck on the grey logo for a bit but then proceeded to go to a black screen that said " No bootable device - please insert a bootable device and hit any key". I tried hitting keys with he USB in but nothing happened.  I had to eventually remove the USB and reset PRAM to get it to boot into osx again  Is there any way to install windows 7 from a usb on my macbook pro using boot camp?
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I am considering setting a firmware password on my Retina MacBook Pro for security reasons. If I do this and later lose the password (or other such extenuating circumstances), how can the data be recovered? Is it even possible?
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I have a late 2013 27" iMac running  Yosemite, and it randomly shuts off every now and then. I tried everything Reset SMC. Diagnostics, reformat Macintosh HD but still occurs and running out of options.
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Last night, I migrated my MacBook's operating system from 10.10 "Yosemite" to 10.11 "El Capitan". Everything seemed to go smoothly. Happily, regarding my TeX-related work, I am able to use the GUI front ends "TeXworks" and "TeXshop" just fine since completing the OS upgrade. I use MacTeX2015, with all the latest updates installed.  Oddly, though, since completing the upgrade I can no longer run any MacTeX command-line utilities such as texdoc and kpsewhich. (Actually, as I just discovered, I can no longer run pdflatex either from a command line. However, I never do run pdflatex from a command line prompt, so that's not an urgent problem for me -- at least not for now.)  The suggestions given in the posting  do not seem to be applicable to this case, as they all seem to revolve around setting up /usr/texbin correctly -- /usr/texbin is no longer allowed under MacOSX 10.11. The document  by Herb Schulz deals in depth with adjusting settings in the GUI front ends, but it appears not to touch on what to do about /usr/texbin, which appears to be the now-missing link to TeX's command line utilities.   Pointers and solutions most welcome!