As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TASK CARD OF OPS CHECKING OF EMERGENCY LIGHTING SWITCH JOB CARD NR 335003 THE EMERGENCY BATTERY PACKS FAILED DURING TEST (REPLACED PACK ) 21 LN LOCATION OF BATTERY PACK. REMOVED AND REPLACED SN AS REQUIRED. PERFORMED CHECKS IAW MFG MM. ALL CHECKS GOOD.