Yes, the battery circuitry was destroyed by corrosion, but the board has no sign of it. Here are my tests: https://docs.google.com/spreadsheets/d/1QaLW4DIwtzQ_cwxgZPA67RDwPTHAB4m2lv5B8M-XlXw/edit#gid=0
PP1V_PRIM 0 V probably means dead PMIC, 338S00267 and nowhere to find it currently.