As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
M/D L4 DOOR EMERGENCY LIGHT POWER SUPPLY M33407 BATTERY FOUND LOW CAPACITY DURING DEEP-CYCLE TEST,REF HAECO NON-ROUTINE NO. 9498879 - ORIGINATED BY EMP V903218,SPEC NO.B777-33-3-7019. PERFORMED BY EMP V903218 - REPLACED M/D L4 DOOR EMERGENCY LIGHT POWER SUPPLY M33407 BATTERY AND C/O NEW BATTERY PACK TEST THE RESULT FOUND NORMAL AS PER AMM 33-51-06-960-802 REV 102.