Well, this sucks of course. Apple is to blame and should repair it for free, etc. But now I'm just curious as to 'how' this would work. Is there some sort of EE

Well, this sucks of course. Apple is to blame and should repair it for free, etc. But now I'm just curious as to 'how' this would work. Is there some sort of EEPROM, flash or controller on that board that gets loaded with new settings or firmware? I know Big Sur does some UEFI upgrades, but would that extend to the I/O board? Or is that a separate payload? Or perhaps the update is only for the SMC or Intel firmware which crashes with certain I/O boards during init and then once init is complete it can cope with any I/O board next boot?