Answer to: My Toshiba laptop powers up, but the screen is black.Something funny - my own very very dim screen problem problem turned out to be Toshiba's eco setting which set brightness to 1. I had accidentally pressed a button that switches it on. The display is so dim it looks off, unless you shine a flashlight on it. Connecting to external display and undoing the eco setting solved it. This was post Windows 10 though, I'm posting it here in case it helps someone.