As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: 13WL BATTERY OF THE EMERGENCY POWER SUPPLY UNIT FAILED EMERGENCY POWER SUPPLY UNIT BUILT IN TEST EQUIPMENT TEST IN REFERENCE WITH JOB CARD 26L00005005. REMOVED AND REPLACED 13WL BATTERY OF THE EMERGENCY POWER SUPPLY UNIT IN REFERENCE WITH AMM 33-51-38.