After cleanup, everything worked fine — except that the PSU’s 5 V became 6.5 V during the accident, and the EPROM with LocalTalk interface firmware died ... defective EEPROM after an ...

What could go wrong, I²C edition, and Embed With Elliot, I²C bus scanning. Serial EEPROM die picture, By Epop (Own work) [CC0], via Wikimedia Commons.