As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 390 MCO-LGA, CREW DECLARED EMERGENCY AND AIRCRAFT DIVERTED TO JFK DUE TO BRAKES HOT ECAM ILLUMINATED. ON TAKEOFF AT ROTATION THE LEFT BRAKES WERE SHOWING 125C WHEN CLEARED FOR TAKEOFF AND SPIKE TO 300C INSTANTANEOUSLY ON ROTATION. BRAKE TEMPS WERE NORMAL ON LANDING ROLLOUT. REMOVED AND REPLACED SAFETY VALVE IAW MM 32-42-36. OPS CHECK GOOD.