I recently had a pretty major problem on my mac.
The ‘Master Firmware Password’ appeared to have been set on my new Macbook Pro, but I don’t remember ever setting one. The firmware lock prevents you from choosing boot up options like holding down ‘alt’ to select a startup disc, or using cmd-R to enter recovery mode.
I hit a problem when my Bootcamp installation become corrupt. Windows 7 wouldn’t start and I couldn’t get it to boot off the recovery USB stick that I made. So I thought, no problem, we can just boot back to OS X. But that’s when the problem started.
Because for whatever reason I had the firmware lock, it wouldn’t let me choose OS X as the startup disc. My Mac was effectively bricked. Stuck on the Windows 7 side, which itself didn’t work. It would not boot OS X, and holding down the alt key sent me to a grey screen with a giant padlock and a password box.
I couldn’t for the life of me remember setting a password. It was a brand new machine (a few months old) so it seemed odd to have a firmware password set, when it is usually turned off by default. After reading pages and pages of forum posts from the Apple support website and endless googling, I stumbled upon the answer: Find My Mac.
I will now give you my solution: When I first got the laptop, I setup ‘Find My Mac’ as most people do. Months ago I tried to test a ‘remote lock’ of the mac from the website. I expected a remote lock to prevent user access in the OS, a bit like the iPhone lock screen. To my dissapointment the lock function didn’t seem to work, nothing happened on my screen, and it just seemed to have failed. I completely forgot about this, until now.
You see, when you do a ‘lock my mac’ from that website, it turns out some sort of bug (or maybe it’s meant to do this, I don’t know?) actually locks the FIRMWARE password of the mac, using the password you entered on the website as the firmware lock password.
So to solve the problem, all I had to do was remember what the password I entered into the ‘Find My Mac’ website was all those months ago. Thankfully it turned out to be ‘1111’.
So if you find your mac’s firmware has suddenly become locked, the password might well be one you entered into the ‘Find My Mac’ website to lock the device. It will save you a lot of time and messing about with visiting an Apple Store to try and reset the password.