Which particular product failed? North bridge or something?

Nothing specific. I was thinking on some early 80s asics.

A full on overheat/overpowered KAPOW PHUT *mini mushroom cloud* usually has the package bulged and the die cracked. But mysteriously dead, usually means a single semiconductor device on the die had a problem, burned out less spectacularly. I think the bonded wiring is usually pretty stout unless subjected to mechanical shock, maybe more so when hotter, generally I think it will carry a heck of a lot more current than what can burn inside. Occasionally, with funky substrates and wires, whisker problems will occur, where a tiny sliver of crystal will short something, happened a lot with germanium transistors, doesn't happen with normal silicon but if it's exotically doped for some special property it can happen.... also might happen if any parts are tinned at very low storage temperatures.