My dad bought a used 21.5 iMac (2017) a few weeks back (previous owner bought it new but decided to sell after a week, so its basically new.) Given that it came with a 1TB fusion drive, we decided to switch it for the Samsung EVO he was using in his previous Macbook (He doesn’t need storage, only speed.)

All went according to plan in terms of opening and swapping the drives, but upon rebooting (attempting to ctrl+r to boot menu) it popped the apple logo and then swapped to a black screen with a lock and password field. After a little reading on the subject it seems someone must have enabled the EFI Firmware password protection which doesn’t allow booting on other drives e.g. external or otherwise.

I’ve contacted the previous owner, but she's drawing a blank, claiming never setting up anything of the sort. I’m unsure if this can be enabled during first boot installation, but she didn’t strike me as the type who would know how to do so afterwards (let alone think about it.) My guess is that the shop might’ve had it returned from a prior owner, not reset it correctly and resold it as new (or perhaps discounted, hard to tell from the receipt.)


Knowing firmware is locked with an unobtainable password ...

  1. Would I be able to remove the new SSD and insert the original HDD and have the password prompt go away? Or is the system locked until correct password is entered, no matter the drive (it booted prior to switching drives).
  2. Warranty void on opening and swapping diskdrive? Searching around it seems everyone has a different story. Some say the rest of the system is still under warranty, others do not. This isn’t Apples issue of cause, but I would likely levy it against the reseller.
  3. Even if the old HDD would work again, I’m assuming that not having the FW password would be a roadblock if reinstalling OSX in the future?

1 Answer 1


This Apple document tells you everything you need to know about Firmware passwords.

The essential points for you are:

  1. Your Mac asks for the firmware password only when attempting to start up from a storage device other than the one selected in Startup Disk preferences, or when starting up from macOS Recovery.

  2. If you can't remember your firmware password or passcode, schedule an in-person service appointment with an Apple Store or Apple Authorized Service Provider. Bring your Mac to the appointment, and bring your original receipt or invoice as proof of purchase.

The Firmware password is not required for OS installation.

You will need to ask the original purchaser for their receipt or other proof of purchase.

  • Thanks for the reply Benwiggy :) So Basically it should work again if we poped back the original hdd?
    – Ills
    Dec 23, 2019 at 15:43
  • It will reboot to the HDD if that's the default startup drive. I'm wondering whether the SSD with a valid system and the same volume name would work in its place. Can you boot to Target mode, and install the OS from another Mac? But really, you need to get this sorted.
    – benwiggy
    Dec 23, 2019 at 16:00
  • As of now, turning it on boots straight to the lock screen (can't even used ctrl+r). Unfortunately I was a big dum dum and "glued" it back together with new stickers before booting it up (having literally done the procedure on his macbook), so accessing the drives will require resealing (hence me asking first =D). Talked to the company who sold it originally, who claims its brand new, but they will contact their supplier. I might try to mirror the drives, but most likely we'll take it to apple for a reset. I really hope they don't charge a fortune for it though. Thanks a lot for the support :)
    – Ills
    Dec 23, 2019 at 16:29
  • I heard something about new machines having a t2 chip that locks the machine to a particular drive. Not sure if you turn this feature on in some way. Dec 23, 2019 at 22:45
  • I recommend you bring the original owner along with the receipt. May want to call ahead of time. Dec 23, 2019 at 22:46

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