What was found
UPON APPLYING EXTERNAL POWER BATTERY BUS RELAYS WERE BURNT. REPLACED RELAYS AND POWER WAS RE-APPLIED AND RELAYS BURNT AGAIN AND SEVERAL CIRCUIT BREAKERS POPPED IN THE COCKPIT. FOUND A LARGE WIRE BUNDLE WITH BURNT WIRES AND CLAMPS APPROXIMATELY 20 INCHES ALONG THE HARNESS IN THE ELECTRICAL PANEL AT THE L-1 DOOR. OPENED HARNESS AND FOUND A SCREW HEAD PROTRUDING FROM THE WALL WITH SEVERAL BROKEN WIRES AROUND IT. CURRENTLY UNDERGOING MAINTENANCE. SYSTEM GROUND CHECK NORMAL OPERATION.