As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: EMERGENCY POWER SUPPLY UNIT 13WL SHOWS SEVERAL FAULTS DURING SYSTEM TEST. FOUND R4 DOOR ESCAPE SLIDE CAUSING THE FAULT AND REPLACED IT PER TASK CARD 26L00025011. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.