As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A DEFUELING PROCEDURE WITH THE AIRCRAFT BATTERY DISCONNECTED AND THE GPU CONNECTED. THE BATTERY SWITCH TURNED ON AND AFTER APPROXIMATELY 30 MINUTES INTO THE DEFUELING PROCEDURE THE RIGHT HAND ELECTRICAL MASTER BOX STARTED SMOKING. WE QUICKLY DISCONNECTED ALL ELECTRICAL POWER TO THE AIRCRAFT. THIS OCCURANCE ALSO BLEW AN 8 AMP IN THE BATTERY MASTER BOX AT (F2) LOCATION.