Actually giving up on this. On closer inspection the connector between the two boards is gunked, and while reflowing the existing chip, some flux cleaner got underneath the display ribbon connector and dissolved some of the conductive adhesive (?) that bonds the LCD drive signal lines to the LCD ribbon.

I bought this radio as an ornament really, so I'm fine with it being non-functional. Maybe one day if another pops up I'll have a donor for bits to fix another anyway.