A bit of a long shot, I had a 'Sky' branded tv just like this some time ago I only know this because I also got a DMTech with exactly the same chassis, On the main board there was a 8050SD regulator, 5Volt 3amp with shutdown pin if my memory serves me correctly. Check that baby! Worth a try I guess.
That was the suspect on mine. I have to admit that I removed the 8050SD from another chassis to repair it. I couldn't source a new part.
HTH
BUFM...