Sky + on, but no functions working?

My Sky + box, which is a Thomson make (approx 18 months old) will go to green light and look as though working, until you press any button that is, even on the box. It won't turn off, change channel, or anything. The only way to switch off is at the wall. I've read the threads on here about resetting where box is stuck in standby - would the same procedure cure this problem? Any help gratefully received!