As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL/JAX - FLT 1495 - ON CLIMB-OUT FROM PHL AT APPROXIMATELY 500 FEET, THE MID-CARGO DOOR WARNING LIGHT ILLUMINATED. FLIGHT RETURNED TO PHL AND LANDED OVERWEIGHT WITH NO FURTHER INCIDENT. MAINTENANCE FOUND THE MID-CARGO DOOR VENT HANDLE OPENED. THEY CHECKED OPERATION OF THE HANDLE AND FOUND IT TO OPERATE NORMALLY. THEY ALSO PERFORMED AN OVERWEIGHT LANDING INSPECTION. (X)