Doesn’t power on for parts only

The condition of the parts are excellent Unfortunately it doesn’t power on.

I tested the unit at the shop I work at, installing big crane's. I put power to the unit, couldn't get it to turn on. I charged the battery, checking with a multimeter and could feel the battery getting "warm". The battery took the charge, but immediately dropping in voltage when pulling the power away from the battery. I'm not sure if the unit just needs a new battery, or if the unit all together is no good. From my understanding , it seems likely it would need a new battery but am not sure.