As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. STL-DFW FLIGHT ABORTED TAKEOFF AT LESS THAN 40 KNOTS DUE TO TAKEOFF CONFIGURATION WARNING INDICATION. BRAKES MADE A LOUD SQUEALING SOUND. PERFORMED TAKEOFF WARNING SYSTEM TEST IAW AMM 31-51-00-730-803 AND BITE FSEU IAW TSM 27-51-00-810-801. CLEANED PARKING BRAKE SHUTOFF VALVE CONNECTOR. OPERATIONAL CHECK GOOD.