What can cause a samsung UA40J5000ARMW not to on

@itxyungi you say there is current flowing in it. If that means that there is power going to the power board but your TV is not turning on, check the fuses on your board and make sure that you have power on those. You also need to check the power on all the other connectors. that way you know where the power goes to and where it stops. Samsung is also known to have issues with their capacitors. Check those and see if they are domed or leaking. Post a couple of pictures of your boards with your question. that way we can see what you see. Use this guide Adding images to an existing question for that.