Downgrading the System Firmware on a Mid-2012 15" Retina MacBook Pro
EDIT: It turns out the reason flashrom couldn't flash the ROM is because the system was not in programming/FW update mode. To enter programming mode, simply hold the power button down (while the system is off) until the boot screen appears, and from there boot Linux. Flashrom will then be able to flash the ROM successfully.
In this video, I go over the process of downgrading the system firmware on my Mid-2012 15" Retina MacBook Pro, in order to get the classic pre-Yosemite white EFI boot screen. Since I primarily use Mac OS X 10.9 Mavericks on this machine, having the classic white boot screen fits much better, and looks much nicer during the booting process. I would highly advise against trying this yourself unless you have an external EEPROM programmer, but if you'd like to, here is a copy of the dump taken from my machine with the old boot ROM version: http://dosdude1.com/files/macstuff/ap...