This seems to be some 3 years old. Be sure you don't pay more for the repair than for a new TV.
My 55inch LG 55LA6900 LED tv wont turn on. I got it as a gift from a friend a week ago but a couple of days ago I noticed flickering when the tv was on. A day after that it would turn on momentarily, show the LG screen and turn itself off immediately (note: no sounds or flashing light noticed). Now it wont even turn on.