As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING LOADING OF C2 BIN, SPARKS WERE SEEN COMING FROM UNDER LEFT SIDE BALLMAT IN DOORWAY OF BIN, WHEN CIRCUIT BREAKER TRIPPED, SPARKING STOPPED. DISCONNECTED ELECTRICAL POWER CONNECTIONS TO LOADING PANEL CONTAINING CIRCUIT BREAKERS RENDERING LOADING SYSTEM INOP AND DISPATCHED A/C PER MEL 25-52-00.