I tried all the things listed, except the real complicated stuff. Turning off and on and off and on and off and on and off and on, no results. Finally noticed that as I closed the lid I saw a flicker of light. Turned out I have this exact problem, but it's nothing more than a bad circuit or worn wire. The screen works fine as long as the lid is only open about 6 in, so at least I can use it until I find the right diagram or information on how to fix the connection.