As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU WILL NOT START. REPLACED IGNITER PLUG, NO HELP. REPLACED LEAD, NO HELP. REPLACED EXCITER. REPLACED APU COOLING AIR SHUTOFF VALVE. REPLACED APU AIR INLET DOOR ACTUATOR. NUMEROUS APU STARTS ACCOMPLISHED, ALL OPS & INDICATIONS NORMAL.