As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REVEIVED APU FIRE INDICATION AFTER APU START, C/W QRH MSG CLEARED IN 5 SECONDS. ALSO HAD APU FIRE FAIL AND APU ECU FAULT CAUTION MSG'S -ALL MSG'S CAME ON AT THE SAME TIME APU FIRE BOTTLE NOT BLOWN. AIRCRAFT REMOVED FROM SERVICE. FOUND APU FIRE PUSHBUTTON ENGAGED, DISENGAGED APU FIRE PUSHBUTTON. AND PERFORMED OPS CHECK OF APU FIRE EXT SYSTEM IAW AMM 26-22-00. OPS CHECK GOOD.