This sounds like a hardware failure rather than a software issue which would be associated with Smart TV.
In most cases these devices are uneconomical to repair, however if you can provide me with your postcode I can recommend a repair centre for you, and they can then give you a quote.
If the unit working with the exception of the display it could just be a lose cable, or faulty LCD display which would be a quick fix, certainly worth taking it in and getting a quote.
I have referred a few customer in MK to BDS, they have always done a great job and only heard good things from those who I refer there, they should be within 5 miles of you too which is a bonus, their number is ***** 769697.
Please let me know if you need any further advice.
John sorry for the inconvenience I had thought I arrange for a Pioneer hifi to be repaired not long ago, I must be mistaken.
I have spoken to a colleague who suggested Richer Sounds, as the approved service centre list here, dont have any near you. Richer Sounds are closed until noon, so I will give them a call and check they can do the repair, from what my colleague has said you drop it into any of their stores (one is near the Milton Keynes Train station) and they send it to their Head Office for repair, and normally offer a fixed price repair.
Ok I will leave it with you, please let me know if you run into the same issue, at which point it would be a case of posting it to one of the approved centres on the list, but by which time it will probably be uneconomical to repair due to postal charges.