What was found
AFTER PUSH BACK APU STOPPED, PULLED BACK INTO GATE. TOLD APU ON FIRE, PERFORMED APU FIRE PROCEDURES. REPLACED APU.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
AFTER PUSH BACK APU STOPPED, PULLED BACK INTO GATE. TOLD APU ON FIRE, PERFORMED APU FIRE PROCEDURES. REPLACED APU.