As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAULT LIGHT ILLUMINATED AFTER START. SHUTDOWN APU. FAULT LIGHT WENT OUT. TRIED SECOND START, SAME OCCURANCE. ACFT GROUNDED. R & R APU STARTER GENERATOR REF MM 49-41-21. STARTER GENERATOR INSTALLATION TEST CHECKS GOOD. LEAK CHECKED GOOD. APU BITE CHECK SHOWS NO FAULTS IAW MM 49-61-00-700-801.