As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT CREW WAS UNABLE TO OPEN FLIGHT DECK DOOR UPON ARRIVAL BY TURNING THE HANDLE. FLIGHT CREW OPENED THE DOOR WITH THE FLIGHT DECK DOOR ELECTRONIC UNLOCK CONTROL. MAINTENANCE REPLACED FLIGHT DECK DOOR LATCH MECHANISM PER AMM 52-51-21 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK WITH NO ISSUES NOTED.