As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS - AFTER ENGINE START AIR PACK 2 REG FAULT BLOCK TURN BACK. PERFORMED WIRE CHECK & INSULATION CHECK PER TSM 21-52-00-810-813-A RAN BOTH ENGINES NO PACK 2 FAULT DETECTED. REMOVED AND REPLACED PACK CONTROLLER 2 PER AMM 21-53-34. SYSTEM TEST OF PACK CONTROL & INDICATING SYSTEM SUCCESSFUL.