I would imagine at that age bitrot would be a problem, no?
I had that happen to a 286 motherboard that I kept in storage (it was new in box, only powered up upon purchase and kept as a spare for a production system). Powered it up a couple of years ago to find the BIOS chip was corrupted, and it could not finish POST.
Still looked brand new from factory though.
I would imagine that even if the apple was in perfect working order, it would not be bootable until the BIOS equivalent was reflashed.