As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU START UNSUCCESSFUL ON TAXI IN. FAULT LIGHT OBSERVED. ACFT GROUNDED. TROUBLESHOOT IAW FIM 802, NO FLAME SHUTDOWN. FOUND INOPERATIVE IGNITION SYS, R & R IGNITION UNIT IAW AMM 49-41-31. R & R APU PLUG & LEAD IAW AMM 49-41-00. APU OPS CHECK NORMAL.