As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING 2 SERVICE CHECK FOR EMER LIGHTS, HAD EPSU BATTERY AFT L MSG AT DOOR 1L TEST PANEL. REPLACED EMER EXIT LIGHT BATTERY PACK AT AFT LT DOOR & EMER EXIT LIGHT BATTERY ASSEMBLY AT LT OVERWING EXTERIOR. ACCOMPLISHED EMER LIGHT TEST. OPERATIONS CHECKED NORMAL.