The electric car refuses to start and indicates "Verbindung prüfen"? In such a scenario, if you haven't already, disconnect the charging cable. Conclude the charging process by removing the cable from the plug socket on the vehicle and detaching it from the charging station. Store the charging cable in the trunk. Now, you should be able to start the vehicle.
Note that depending on the type of vehicle, you might still need to "unlock" the charging cable. Refer to the E-car instructions for guidance on how to open the socket flap specific to your vehicle type.