I bought a used MRC Tech IV 260 power pack. I put a meter on it and the voltages were perfect. I cleaned the face of the controller with alcohol and let it dry for 24 hours. Now . . . . dead. Will not power up. The screws that hold the controller together seem to be proprietary / similar to a rivet so I haven't been able to open the box. Do I have to drill them out ? Is there an internal fuse ? Are these boxes repairable or did I somehow kill it ?