I think that the switch behind the dual button has stuck
should hopefully be a pretty easy dlr fix if that is the case
might even be worth connecting up the tyre pump from the boot, and blowing air around the button area incase its something as simple as a bit of leaf or gunk stuck behind it
wouldn't try anything more complex than that though - if it doesn't fix it, leave it to the dlr - think you probably need to take the dash apart to get at the switch, and whilst it's not a HUGE job to do that...