As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING GROUND OPERATION, ACS ALERTED MAINTENANCE TO SMOKE FROM APU AREA. MAINTENANCE OPENED LT APU ACCESS DOOR AND FOUND APU STARTER ON FIRE. CLOSED ACCESS AND BLEW NR 1 FIRE BOTTLE. APU REMOVED AND COMPARTMENT INSPECTED AND CLEANED. NEW APU INSTALLED. A/C WIRING INSPECTION AND STARTER RELAY REPLACEMENT IN PROGRESS.