As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU MAINTENANCE AND FAULT LIGHT CAME ON DURING SHUTDOWN OF THE APU. RAN THRU QRH, LIGHTS WENT OUT. AFTER LANDING, ATTEMPTED TO START THE APU AND THE SAME TWO LIGHTS CAME ON. ACFT GROUNDED. REMOVED AND REPLACED START CONVERTER. START CONVERTER INSTALLATION OPS TESTS GOOD. GROUND VERIFICATION SUCCESSFUL IAW AMM 49-41-61-400-801, AND 49-61-00-700-801. LEAK AND OPS CHECKED GOOD. NO MAINTENANCE MESSAGE ON CDU.