As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CREW PREFLIGHT, APU WOULD NOT START. PERFORMED FIM 49-40-00 FOR A (NO FLAME SHUTDOWN) MESSAGE SHOWN FOR APU BITE ON THE CDU. VERIFIED APU IGNITION AND STARTER OPERATION AS NORMAL. VERIFIED FUEL FLOW. REMOVED AND REPLACED FUEL CONTROL UNIT. (K)