As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: DURING TROUBLESHOOTING ON EMERGENCY POWER SUPPLY UNIT 10WL FAULT MESSAGE MAINTENANCE FOUND THE R1 DOOR SLIDE WHICH WAS JUST INSTALLED WAS INOPERATIVE AND WAS BAD FROM STOCK DUE TO A BROKEN BACK PLATE. THE SLIDE WAS REMOVED FROM THE AIRCRAFT AND A SERVICEABLE SLIDE WAS INSTALLED.