Black screen, no logo and already replaced LED backlights

Black screen, no logo and already replaced LED backlights

My LG TV (model 47lb580v) had faulty back lights which were replaced and are now fully functional. However, when I turn the TV on the backlight kicks on but I don't have any picture at all. I have triple checked all of my connections and replaced the main board, audio board and the t-con board but I have no picture at all. Not even the LG logo comes on when I turn the TV on.

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