As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: FAULT EMERGENCY POWER SUPPLY UNIT 12WL IN PASSENGER CABIN. PERFORMED OPERATIONAL TEST OF FAULT CONFIRMATION PER TSM 33-51-00-810-822-A THE EMERGENCY POWER SUPPLY UNIT (12WL) MUST BE REPLACED AT CABIN PASSENGER PER AMM 33-51-38-400-001-A THE EMERGENCY POWER SUPPLY UNIT (12WL) WAS REPLACED AND PERFORMED OPERATIONAL CHECK OF THE EMERGENCY POWER SUPPLY UNIT PER AMM 33-51-00-710-001 TEST IS OK.