As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND BURNED AND MELTED WIRE INSULATION STARTING AT APU GENERATOR CIRCUIT BREAKER (C803) AND RUNNING APPROXIMATELY 18 INCHES INTO WIRE BUNDLE (BLUE AND YELLOW PHASES). REPLACED APU GENERATOR CIRCUIT BREAKER AND REPAIRED WIRING TO THE CIRCUIT BREAKER. RAN APU AND CHECKED BREAKER WITH HEAVY ELECTRICAL LOAD. CHECKS O.K.