As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DURING EMERGENCY POWER SUPPLY UNIT OPERATIONS TEST 13WL EMERGENCY POWER SUPPLY UNIT FAULTED. REMOVED AND REPLACED EMERGENCY POWER SUPPLY UNIT BATTERY 13WL AND REPLACED EMERGENCY POWER SUPPLY UNIT PER AMM 33-51-00 OPERATIONS CHECK GOOD.