As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 4167, FIRST OFFICER AND THE FLIGHT ATTENDANT REPORTED THEY WERE UNABLE TO OPEN MAIN CABIN DOOR FROM INSIDE. GATE AGENT OPENED DOOR FROM OUTSIDE. AIRCRAFT REMOVED FROM SERVICE. FOUND MAIN DOOR INTERNAL HANDLE NOT PROPERLY SECURED. SECURED HANDLE IAW AMM 52-18-05. OPS CHECKED GOOD IAW AMM 52-18-00. AIRCRAFT RETURNED TO SERVICE.