A latch release backup system for a latch assembly of a motor-vehicle door is provided with a key cylinder configured to receive a vehicle key and which is rotatably mounted to the motor-vehicle door, and a mechanical coupling arrangement mounted within the motor-vehicle door and operable to convert a rotation of the key cylinder into actuation of an actuation group of the latch assembly for causing latch release. The key cylinder defines an electrical interface socket designed to receive the vehicle key. An electronic control unit is mounted within the motor-vehicle door and is electrically connected to the electrical interface socket to receive identification information (Id) from the vehicle key when plugged into the electrical interface socket. The mechanical coupling arrangement is normally disengaged from the actuation group of the latch assembly, and the electronic control unit is configured to control selective engagement of the mechanical coupling arrangement to the actuation group of the latch assembly based on the identification information (Id) received from the vehicle key.