Prius gen 4 (UK) I am sure I picked up this Info from a forum ---May have been the Prius Chat and thought I would share. Method Press the lock button and whilst holding the lock button down . Press the unlock button twice- red light blink twice Unlock or deactivating --Press the unlock button on the key fob Try it by moving the fob next to the door. In my case, the car didn`t respond! It appears the key fob has gone to sleep.