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 AT THE L2 DOOR FAILED THE EMERGENCY LIGHTING SYSTEM TEST PER TASK CARD 26L00025010. REPLACED EMERGENCY POWER SUPPLY UNIT BATTERY AND ACCOMPLISHED A SATISFACTORY OPERATIONAL PER AMM 33-51-38.