As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DESCENT TO IAH DURING APU START, RECEIVED AN APU FIRE FAIL STATUS MESSAGE, FOLLOWED BY AN APU FIRE WARNING MESSAGE. PUSHED THE APU FIRE SWITCH AND RECEIVED NO FIRE INDICATIONS AFTER THAT. RAN QRH AND RECEIVED APU FAULT MESSAGE. FOUND EXCESSIVE OIL FROM THE OVERSERVICED APU. ALSO FOUND APU DOOR WILL NOT OPEN. REPLACED APU ECU. OPS CHECK GOOD.