As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: CIDS (1) EMERGENCY POWER SUPPLY UNIT (10WL) BATTERY FAULT OF EMERGENCY LIGHTS. MAINTENANCE REPLACED EMERGENCY POWER SUPPLY UNIT BATTERY PACK (10WL) PER MM 33-581-38 AND PERFORMED SATISFACTORY OPERATIONAL CHECK.