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 PERIODIC SERVICE CHECK OF EMERGENCY POWER SUPPLY UNIT BATTERY SYSTEM TEST MAINTENANCE FOUND EMERGENCY POWER SUPPLY UNIT 10WL BATTERY FAULTED. REPLACED BATTERY FOR EMERGENCY POWER SUPPLY UNIT 10WL AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.