@dannyh41496 since you already replaced all the LCD backlight strip (I assume that is what you meant by led interface strip and all leds) as well as the power board, it stands to reason that your TV does not get a backlight on signal from the main board. Turn your TV off. Disconnect the power cord from the power board. Disconnect the main board from the power board. Now plug your power cord back into your power board. Your backlights should now turn on. No, you will not have a picture etc and only your LED lights should be on. You can see those through the multiple holes in the sheet metal on the back of the LCD panel.