TV has power, but no video
So I am trying to troubleshoot a insignia tv. There is no video, the screen stays black. When I turn the tv on or off the light on the tv changes, so there is power. I also tested the cables on the boards and they all have power going to them. There is three boards, one that is power and the ac adapter plugs into, the other one is where the hdmi Cable and other cables plug into, and the last one plugs into the screen.
How do I yroubleshoot the tv and figure out which board is bad or if it is the screen?
If there is any other information you need please let me know