Module (10) for controlling usability of a processing unit (2) of a device (1), the module comprising a modem (11) for communicating with a cellular network, and an access circuit (12) connected to the modem for cellular network authentication and access, which access circuit comprises or is connected to a secure element (12), characterized by a state machine configured to control the device in accordance with one of a plurality of usability states, including at least a normal state and an alert state, wherein operation of the processing unit is inhibited in said alert state.