'''++rscillion0311++''' all that the lights installed show you is that your USB port gets power. You will have to remove the back cover from your TV and take a look at the power board as well as the main board. Measure the voltages on the power board and let us know what you get. Disconnect the wire from the power board to the main board and see if your TV’s backlight comes on. Post some good pictures of your boards with your QUESTION. That way we can see what you see. [guide|21499]
For now, this does sound like a power board failure.