Someone showed me their iMac that they recently bought second-hand. It boots normally to the login screen with the PIN (EDIT: it is a PIN and NOT a passcode; the message reads "Enter your system lock PIN code to unlock this Mac."). I'm trying to circumvent that by reinstalling OS X via Disk Utility, however the Command+R combo on boot brings me to a screen with a picture of a lock and a password field, no text. Extensive internet searches have yet to even acknowledge that this is a thing that can happen. What do I do short of disassembling this, removing the HDD, and going from there?

  • 1
    It has been a while, but if memory serves me correctly, I think that before Lion, you needed a recovery disk or a connection to the internet to do what you want to do. If their iMac has OS X that predates this, then that is likely the problem.
    – AMR
    Commented Aug 18, 2015 at 19:14

2 Answers 2


The issue I was experiencing was due to a firmware lock, likely triggered via iCloud. Because it is a late 2012 model, bypassing the lock is no longer possible by removing a stick of RAM and resetting the PRAM. It is locked-out by an EFI chip that executes the lock routine before booting. My only options er on the side of more extreme hacking (via reflow solder gun).


This means the hard drive is encrypted. Boot the machine up, go to System Preferences > Security > FileVault and enter the password to decrypt the volume.


If you don't have access to the drive/password, force boot to Internet Recovery by holding [CMD] + [OPTION] + [R] and you should see a spinning globe (you'll need to have Internet access). More info here: https://support.apple.com/en-us/HT201314

Once Internet Recovery is booted up, because you're not using the HD to boot, you should be able to wipe the drive and reinstall, even if it is encrypted. Info on that here: Lost password on Mac OS Extended (Journaled, Encrypted) Drive. Want to reformat it

NOTE: Internet Recovery requires that the Mac has OS X Lion or later. Internet Recovery is essentially the same as using the ol' Snow Leopard disc to boot.


That message means that someone has locked out the Mac as a security measure using Find My Mac within iCloud. There is some hefty ways to get around that (http://forums.macrumors.com/threads/how-to-unlock-system-lock-pin-code.1438822/), but since it is purchased used, the only reasonable solution would be to install a new Hard Drive or contact the previous owner and obtain the PIN.

  • I see. But the issue is neither I nor the owner know any of the credentials associated with this machine, and assume we'll be unable to obtain them. I'm pretty adept with all things PC, but I've never seen an issue like this. Anything I can do without a screwdriver (or in Apple's case, a hair dryer :/)?
    – Busman
    Commented Aug 18, 2015 at 19:10
  • Made an edit to my answer. You certainly can reinstall a hard drive manually, but I think you should be okay with Internet Recovery. Commented Aug 18, 2015 at 19:18
  • I'm still getting a picture of a lock, a password field, and button with a right-arrow to submit the password. No labeling text or feedback text from entering wrong passwords. I'm stumped. It's like a complete, total system lock-out. Are these some kind of anti-theft measures?
    – Busman
    Commented Aug 18, 2015 at 19:27
  • The only anti-theft measure I'm aware of is Lost Mode for Find My Device. However, if the machine were in Lost Mode, you'd likely see a 4-digit PIN request and not a password field with an arrow. Perhaps the Internet Recovery isn't working properly. Confirm, are you trying to initiate Internet Recovery using the method listed here? cultofmac.com/106669/… Commented Aug 18, 2015 at 19:36
  • And are you sure it has OS X Lion or later? Commented Aug 18, 2015 at 19:45

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