find the pin behind the shifter with the orange top and press it down.. if it doesn't go down, keep trying or once you actually get the "click" to happen when on the brake then try and engage this at that stage
once you get this presed down, hold it down, and get a black cable tie and tie it around the shifter with the fat end of the cable tie above the pressed-down button
tighten it so that the button is permanently pressed down by the cable tie
seriously is has no function.. you could argue that its a good security measure but everyone knows it exists...
my car started doing this once its something to do with the wiring between he brake and the gearbox. i have had zero problems for 3 years with the above fix