As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAS - ABORTED TAKEOFF - FLT 421 - AIRCRAFT ABORTED TAKEOFF FOR POSSIBLE AUTO BRAKE PROBLEM. SAFETY EVENT REPORT REVEALS THAT TAKE OFF WAS ABORTED, UNDER 60 KNOTS, DUE TO TAKE OFF CONFIGURATION WARNING. CREW NOTICED SPEED BRAKE LEVER NOT FULLY IN DETENT AFTER TAXIING OFF RUNWAY. RE-SET SPEED BRAKE AND ATTEMPTED TAKE OFF AGAIN WITHOUT FURTHER EVENTS.