Comment by XorNot

This repair makes the case I've found more obvious though: we need microcontroller firmwares to be made available (I would argue as a public government archive honestly).

I've had several Yamaha amps blow micro-processors or DSPs, and on the older ones there were no firmware upgrades so you just plain couldn't do anything afterwards.

I've got the same problem with the controller for my heat exchange ventilation - microcontroller is dead, and while the chip is easy to get and replace, there's 0 chance I can source a replacement firmware for it.