Another macOS update, and for most another firmware update, this time including Studio Displays. These should go well, but what if they don’t? How do you put your Mac’s firmware back in order or get that expensive display working? Should you force a shutdown and try again? Before panic takes charge, take a deep breath and read on.
Intel (non-T2)
These have fixed ROM and upgradable firmware with EFI software loaded from any bootable storage. Although that means they can’t support any form of secure boot, it also makes them more versatile to recover when there are firmware problems. They’re designed to have ‘self-healing’ firmware: if something does go wrong in a firmware update, the Mac is supposed to be able to restore sufficient to be functional again. As they can be booted from an external bootable disk anyway, they should be straightforward to get back into action.
Read more at eclecticlight.co