As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7638 ORD TO IND, DURING TAKEOFF ROLL ABORTED THE TAKEOFF DUE TO A MASTER WARNING MAIN CABIN DOOR OPEN INDICATION. CLEARED RUNWAY AND HAD F/A CHECK AND RESCUER THE MAIN CABIN DOOR. TAXIED BACK TO THE RUNWAY AND TOOK OFF WITHOUT FURTHER COMPLICATIONS. NO PILOT WRITE UP, NO FURTHER DISCREPANCIES AT THIS TIME.