As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: EMERGENCY EXIT LIGHT BOTH IN SEAT 3L AND 3R DOOR CEILING EXIT LIGHT, TURNED OFF AND ON AND MOST SEATS IN REAR SECTION OF AIRPLANE WERE HAVING PROBLEMS. MAINTENANCE FOUND L3 BATTERY PACK WAS NOT COMMUNICATING WITH CIDS AND MAINTENANCE ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK OF LIGHTS PER AMM 33-51-00.