I've restored use of an old well-worn MX-700 several times by cleaning the circuit board. Eventually the amount of "good use" between each cleaning became shorter and shorter, but it could fix things for you for some time. Eventually the "real" fix is a new rubber keypad, but URC won't send those to end users.

(And after much abuse, two liquid spills and a brief period with corrupt memory, the circuit board from that remote is still going...)