As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING OPS CHECK OF THE CABIN EMERGENCY LIGHTS ON A SCHEDULED CHECK THE NR 3 EMERGENCY LIGHT POWER SUPPLY FAILED. MAINTENANCE MOVED TO DMIL A738356 AND OPERATED IAW MEL 33-51-01-1. MAINTENANCE R & R THE EPSU BATTERY PACK IAW AMM 33-51-17 AND OPS CHECKED GOOD. DML CLEARED AND ACFT OK FOR SERVICE.