Try disconnecting the battery indicator; this can interfere with the battery data lines if liquid damaged, preventing the battery from being recognised.
This is unlikely to resolve the issue though I’m afraid. Sounds like your colleague disconnected the battery with a metal tool, or shorted it another way, which can send battery voltage to the SMC through the data line, killing it. Common issue and hear this happen a lot on the forums. Only solution is replacing the logic board or solder a SMC from a donor board.