Max, I believe these TVs have an inherent problem with their on/off switches. I have just had the problem on a TV less than two years old, which because it is out of Tesco's one year warranty, they will not fix. I would suggest sending the TV to a local repairer which is what I am in the process of doing, the repair should be straight forward, provided they can get the part. I complained to Tesco using one of their forms and they are sending me a payment which should more than cover the cost of repair. You will probably need the receipt though. I have another similar TV,but this is branded TEVION, from Aldi and it has twice had switch failure , which Aldi told me was a problem on these TVS. Their warranty is two years though, so they repaired it twice for me. The switch in the Tevion tv appears to be identical to the one on the Technosonic TV and I suspect they are made in the same factory in China too.
Let me know how you get on,
Philip.
Philip Rolfe
September 2009