What was found
(CAN) SHORTLY AFTER TAKEOFF, FLIGHT RECEIVED "DOOR AFT CARGO" INDICATION. ECAM ADVISED NOT TO CLIMB ABOVE A100, SO DID NOT ASCEND ABOVE. RETURNED TO LAND APPROXIMATELY 7,000 KG OVERWEIGHT. CREW DECLARED A PAN PAN DUE TO OVERWEIGHT LANDING, AND POSSIBLE BRAKE OVERHEAT. REPLACED PROXIMITY S/W 32WV IAW AMM 52-71-12, SERV.