As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT THE APU FAILED TO START WHEN COMMANDED. THE MAINTENANCE VENDOR DETERMINED THAT THE APU INLET DOOR ACTUATOR WAS FAULTY. THE ACTUATOR WAS REPLACED WITH A REPAIRED ACTUATOR AND ADJUSTED AS NEEDED. OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.