As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A ROUTINE OVERNIGHT SERVICE CHECK INSPECTION, MAINTENANCE REPORTED A PORTION OF THE EMERGENCY EVACUATION LIGHTING SYSTEM WOULD NOT TEST. MAINTENANCE REMOVED AND REPLACED POWER SUPPLY BATTERY PACK AND OPS CHECK ACCOMPLISHED PER AMM 33-50-00, OPS CHECKED NORMAL. AIRCRAFT RETURNED TO SERVICE.