You always have to wonder if it's a case of THEY dropped the remote and it stopped working. It may also be that the config is still there, it's just not working (how could they tell if the config is gone). I've occasionally seen times where the firmware needs to be refreshed (reflashed), but normally this is STRANGE operation, not NO operation. So my guess is they dropped the remote, the batteries are drained, or it needs a firmware reflash.
If this situation were common - the Pronto forum would have lots of posts on this situation. I can't remember one in the last few months.
Jim L