As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: FLIGHT DECK DOOR WILL NOT OPEN INFLIGHT UNLESS USING THE FLIGHT DECK DOOR UNLOCK SWITCH. IT APPEARS THAT THE UPPER LATCH IN THE DOOR HAS BECOME DISCONNECTED FROM THE ROTARY HANDLE. MAINTENANCE REPLACED UPPER DOOR LATCH AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 52-51-21.