As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRIOR TO OPERATING THE FLIGHT, THE APU AUTO-SHUTDOWN. THE PILOT REPORTED: APU FAILED AT GATE, HEAVY SMOKE IN CABIN AND OUTSIDE. EVACUATION CHECKLIST RUN. APU FIRE BOTTLE PRESSED. ACFT WAS CLEARED OF PASSENGERS WITHOUT INCIDENT. THE ACFT WAS THEN MOVED OFF THE GATE FOR REQUIRED INSPECTIONS. VERIFIED SMOKE CAUSED BY FAILURE OF APU. R & R APU. RAN NR 1 AND NR 2 ENGINES AND RAN BOTH PACKS FOR 20 MINS TO VERIFY NO RESIDUAL ODORS, NONE NOTED. OK FOR SERVICE.