· Reboot your Mac using the hardware buttons, or if you are already inside the Macintosh being turned on, hit reboot from the Apple icon. Press and hold down Command + R buttons together until the Recovery Mode shows up. Find the Utilities screen and go to Utilities menu bar. Look for the option ‘Firmware Password Utility’.
Boot up your Mac, and you should not see the firmware lock again. Disable the Password With Firmware Password Utility. Restart your Mac while holding down the Command + R keys to enter Recovery Mode. When the Utilities screen appears, go the Utilities menu bar, and select “Firmware Password Utility”. Choose to turn the Firmware Password off.
· That’s the key–when the Mac sees that the RAM configuration has changed (it also works if the Mac contains just one RAM board, and you add one for a total of two, or if you replace both RAM boards with two of a different size), then when you power up and hold down Command-Option-P-R (before the screen lights up) and let the Mac chime three times, it will reset the firmware password.
· Reboot the Mac and hold down Command+R to enter recovery mode. At the Utilities screen, go to the Utilities menu bar item and choose “Firmware Password Utility”. Select to turn the Firmware Password to OFF. If this is successful it will tell you the firmware password is off.
A firmware password on Mac systems locks the hardware to prevent booting to alternative modes that could bypass OS X security, but in order to access some of these modes you first have to disable ...
The prevailing attitude these days seems to be if you don't finish first, you're last.