Issue: I recently received a Toshiba Satellite E45T-A4300 laptop, touch screen, with a rather bizarre issue. The backlight for the LCD was randomly turning off and the client was moving the LCD back and forth to get the backlight back on.
My first thought was probably a loose cable from the LCD to the motherboard. I removed the back LCD panel by removing the two silver screws on each side of the screen and carefully dislodging the hinges from around the bezel. The back panel simply snaps into place. I then removed the under-bezel by removing the 9-10 screws, which granted me a view of the motherboard connector for the LCD wire.
With the computer on, I then moved the cables back and forth to determine if there was a loose or frayed cable along the way. This did not result in any apparent change of condition for the laptop.
Solution: What I did notice was when the backlight turned off, if I pressed on the motherboard directly underneath the power button the backlight would come on. It seems the touch sensor for the power button is also somehow linked to the backlight. The cause of the issue could have been from wear and tear or user damage, but the issue is certainly linked to that portion of the motherboard. I attached a small piece of foam, using electrical tape, to the underside of the motherboard to prevent shorting or inadvertent signaling from the power button to the motherboard. This isn’t a perfect solution but what has worked so far.