After a few days away, switched the box and tv back on and all I got was a 'No Signal' message, Rebooted the box and all I now get is the screen crackling and flashing as it goes through the set up. Once set up has finished the crackling stops and I go back to the 'No Signal' message on the TV. I've tried different HDMI socket on the tv and also a new HDMI cable but problem remains. Any ideas. Thanks.