As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CABIN DOOR WILL NOT OPEN UNLESS " ARMED" AND THEN "DISARMED" A SECOND TIME.-C/A-OPENED MAIN CABIN DOOR IAW EMB 175 AMM 52-11-00-940-001 STEP 3 AND CLOSED IAW 52-11-00-940-003 STEP 12 THROUGH SEVERAL CYCLES. NO FAULT FOUND, DOOR OPENS AND CLOSES NORMALLY.