As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU NO START ON THE GROUND. APU FAILED TO START SEVERAL TIMES. BIT OF ECU SHOWS CURRENT LAST RUN, RUN ABORTED "AC START CIRCUIT". APU DOOR CONTROL SWITCH REPLACED. RAN APU FOR 2 HOURS AND PERFORMED MULTIPLE APU STARTS. APU CHECKED GOOD, NO FAULTS.