Firmware Locked Password [duplicate]

I have an 2012 imac with the most current Update software being High Sierra. I've seemed to have locked the firmware and I can't get passed it I don't have a receipt so no in store help. I've put "resetpassword" in terminal, I've took out the ram, I've made a bookable removable disk, I've put the original DVD that came with it and at this point I have a great looking paper weigjt. Please Help!!!

Solution 1:

Firmware passwords are a security measure intended to stop a stolen Mac from being used. Quite correctly, in my view, Apple won't help you unless you have a receipt or some other way of establishing ownership.

Have a read of this from Topher Kessler which talks about how the firmware protection is implemented and the steps needed to erase the firmware password.

If you do find a way to bypass the firmware password, you probably should not publish it here.