As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY LIGHT BATTERY PACK DEEP-CYCLE TEST FOUND R4 BATTERY M33408 CAN NOT KEEP LT ON 15 MINUTES,REF HAECO NON-ROUTINE NO.V9427552 ORIGINATED BY EMP V905404 SPEC NO.B777-33-3-7019. PERFORMED BY EMP V907744, REPLACED THE R4 BATTERY PACK M33408 AND DO THE INSTALLATION TEST, THE TEST RESULT NORMAL,REF AMM 33-51-06-960-802 REV.90.