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 UNIY 15WL FAILED ON CIDS EMERGENCY POWER SUPPLY UNIT SYSTEM TEST. MAINTENANCE DETERMINED THAT THE L2 DOOR SLIDE WAS CAUSING THE FAILURE MESSAGE AND REPLACED THE SLIDE PER JOB CARD 26L00025012