As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: EMERGENCY POWER SUPPLY UNIT 10WL BATTERY FAILED SYSTEM TEST. MAINTENANCE REPLACED EMERGENCY POWER SUPPLY UNIT 10WL (AALA202302091092) AND BATTERY (AALA202302093470). A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLKISHED PER AMM 33-51-00.