As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AFTER OPERATIONAL TEST OF EMERGENCY LIGHTS ERROR MESSAGE: CLASS 1 ATA 25-62-41, ESCAPE SLIDE LIGHT EMERGENCY POWER SUPPLY UNIT 10WL FORWARD LEFT MESSAGE ON MCDU. REPLACED THE L1 DOOR SLIDE RAFT PER TASK CARD 26L00025011 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK WITH NO FAULTS NOTED DURING THE EMERGENCY LIGHTING SYSTYEM.