Tv flickers and will not turn on or off.

JD Earl depends on what is flickering. This does sound like a power board issue. Since you already tried to reset it, it may just be time now to take a closer look. Unplug your TV and remove the back. Then take a close look at all of your boards but for now focus on the power supply. Check or any obvious damaged components like leaking, domed looking capacitors. Post some good images of all 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