As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON PUSHBACK, APU SHUTDOWN AS CABIN FILLED WITH SMOKE. MTC IN PROGRESS ON APU AND DUCT BURNOUT. FND APU LOW OIL PRESSURE SWITCH LEAKING OIL. REPLACED SAME, NO LEAKS NOTED. WHILE PERFORMING OP 5089 APU AUTO SHUTDOWN FOR LOW OIL PRESSURE. REPLACED ECU AS PRECAUTION REMOVED AND REPLACED APU PER TRANS 9T103, C/W OPN 5089 APU /ENGINE DUC BURNOUT.