As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PRE-FLIGHT INSPECTION, THE AIRCREW NOTICED THE REAR ISLE CEILING EMERGENCY LIGHT INOPERATIVE. GROUND MX CREW REMOVED AND REPLACED THE PS3 EMERGENCY BATTERY PACK. OPS CHECK WAS PERFORMED ON THE EMERGENCY LIGHTING SYSTEM. SYSTEM CHECKED SATISFACTORY. AIRCRAFT RETURNED TO FLIGHT STATUS.