Sony Internet Player NSZ-GS7 no longer working after a week

[blackfrancis75]

I'm not sure if this is the relevant forum, but just incase:
I have a Sony Internet Player that I just started using. It was ok, but seems a bit flaky at first. Now, it won't work at all. When I power it up the 'Sony' logo comes up for about 5 seconds, then it disappears and the TV behaves as though there's no longer any input to the HDMI port. Is there any way to reset the box to factory defaults without using the devices' own on-screen menu? Anything else I can try?
Thanks,

 

[blackfrancis75]

further to this, it works if I plug it into my LCD monitor, but audio and video cut out if I plug it into my TV. Not sure what changed to cause this behaviour. There dont seem to be many settings I can try on my TV.