As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: L1 DOOR POSITION EMER LIGHT TEST SW LIGHT GOES ON AND OFF. PERFORMED MAINTENANCE MESSAGE 33-11407 FAULT ISOLATION. MAINTENANCE REPLACED THE DOOR 4L WELS REMOTE CONTROL UNIT BATTERY IAW B787 FIM DMC-B787-A-33-50-F1-74A-421A-A AMM DMC-B787-A-33-51-07-02B-520A-A/720A-A.