As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FUNCTIONAL CHECK OF EMERGENCY LIGHT SYSTEM THE FORWARD L/H EMERGENCY POWER SUPPLY UNIT FAILED TEST FOR EXTERNAL LOADS FORWARD LEFT AND COMM FORWARD LEFT MESSAGES ON CIDS PANEL. MAINTENANCE REMOVED AND REPLACED EMERGENCY POWER SUPPLY UNIT (11WL), FUNCTIONAL CHECK OF SYSTEM WAS GOOD.