I successfully repaired my CCU which was a process itself. Cutting to the chase, pop the CCU apart and inspect the circuit card. Look particularly closely at the traces on the back of the card, the main connection pins, and the pushbutton area. If you see cracks or rings around the joints, flow in some fresh solder, that's likely all that's wrong. If you see burnt traces or charring, things can get more involved and you may be better off with a rebuilt or 2nd hand CCU.