As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS IN BASE MAINTENANCE: EMERGENCY BATTERY PACK M3303 AT DOOR L3 FAILS CAPACITY CHECK. MAINTENANCE REMOVED AND REPLACED BATTERY PACK M33303 AT DOOR L3 AND INSTALLED TEST CAPACITY CHECK GOOD IAW B777 AMM 33-51-06-960-802 AMM 33-51-06-200-801.