As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PUSHBACK WITH PACKS ON, APU POWER, HAD SMOKE/DUST THROUGHOUT CABIN. APU QUIT TWICE AFTER PUSH. RAN ENGINES AND PACKS - NO SMOKE OR FUMES, CYCLED THROUGH TEMP RANGES ALL CLEAR. FOUND APU FAILED WITH OIL IN THE TAILPIPE AND METAL ON CHIP DETECTORS. DUCT DECONTAMINATION PERFORMED AND APU REPLACED.