As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: DURING OPERATIONAL TEST OF THE EMERGENCY POWER SUPPLY UNIT BY BUILT IN TEST EQUIPMENT CHECK OF SLIDE SHOWN FAILURE ESCAPE SLIDE LIGHT (EMERGENCY POWER SUPPLY UNIT 13WL) AFT IN PASSENGER CABIN. REMOVED AND REPLACED SLIDE ON DOOR L4 PER AMM 25-62-44000-002-A AND AMM 25-62-44-400-006-A.