Yes, there are repair shops in the UK that are authorized to work on this model. You can expect £25 to have the TV examined, and that would be put toward the final repair bill, should you decide to let them repair it.
I do not think this is a soft problem. In fact, we mostly eliminated that possibility by disconnecting everything but the power cord and seeing that the problem continued. Rather, I suspect we are dealing with a defective or damaged main board inside the TV.
That being said, I'm not sure having the TV repaired will be cost effective. Even with the modest evaluation fee, you would probably end up seeing a £150 repair bill full issue, and you can purchase a brand new TV of this size £250 nowadays.
It may simply be a better financial decision to replace the TV in its entirety, as opposed to having it repaired. I do suggest, though, that you have the TV evaluated by a local engineer that can give you a full work up of the problem.
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