OK. This model was designed with a self-diagnosis feature. When something inside the TV fails (e.g. a circuit board) that front panel LED will flash in a certain pattern, and the pattern can tell us a lot about what's wrong.
On your model, the 4-blink code you're seeing means the TV's power supply board has failed and will need to be replaced. Sounds like bad news, but it really could be a lot worse! The power supply for your TV is cheap (£41.99) and it's pretty easy to replace if you have a screwdriver and an hour of spare time.
If you'd like to order the board, >>click here<<. To replace, just disconnect the TV's power cord and remove its rear panel. There are alot of screws, so keep a bowl nearby. Once the back panel is off, you'll see the board in the middle. It should be the only tan one in there, but you can also compare it to the picture I linked you to. To remove it, just disconnect the wiring harnesses (they're just clips, you don't have to solder anything) and then remove the screws that are holding it in place.
To install the new one, just reverse that procedure. It's really a lot easier than most people think! But if you'd rather not repair it yourself, no worries. Just call a local servicer.
Let me know if you need anything else. Oh, and please take a second to rate the service I provided (there should be a 5-star scale on your page somewhere). Don't worry, that won't close your question and you can still respond back at any time.