First things first: usually the opposite happens, meaning the door won't unlock. On Teslas, however, there are also problems when the door opens, the plug is inserted, but charging doesn't start. In this case, seeing the charging door open doesn't mean the car is charging. If charging doesn't start despite the correct connections, there's probably a fault with the cable or the charger. The advice is to try charging at another station and with another wallbox and see how the car behaves. If everything remains unchanged and the battery doesn't start charging, then a new compatible Tesla charging cable may be the definitive solution.