As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAULT LIGHT ILLUMINATED DURING START. FAULT LIGHT EXTINGUISHED AFTER 5 MINUTES. GROUNDED - YES. APU WOULD NOT START, TRIED TWICE. REMOVED AND REPLACED APU EXCITER UNIT IAW AMM 49-41-31-000-801 AND 49-41-31-400-801, ETOPS GROUND FUNCTIONAL CHECK GOOD IAW AMM 49-11-00-860-801.