Have you tried to update software on box. Put box in standby, press and hold back-up button, un-plug mains lead , put mains lead back in while still holding back-up. Should get all led's light up on front panel and screen " updating system software". Let the download finish, box will go into standby, then power up. If it does not respond via remote, it may well be the infra red receiver in the sky box. Try another remote to rule out handset fault.
Tony
April 2009