Panasonic Viera PX600B has no picture or sound?

I have a Panasonic Viera PX600B TV which has just gone phut whilst viewing!!

No picture or sound at all. The standby red LED light blinks 10 times and then goes off, comes back on and blinks another 10 times and repeats.

I have tried switching off at the mains and then switching back on but it makes no difference.

the TV is viewed through a Sky box and the box seems to be functioning ok but it also has an analogue input as well so even if the Sky side was not workiing there would be a signal on that

Anyone out there has any ideas??

thanks