For professional's only. If your screen isn't turning on, but your power button light is on and your keyboard light. There's an easy fix for it. With mine there's a bug in the power management program. So I took my computer apart and disconnected my battery for a minute. After that my screen worked. It resets the power management program. BEFORE you do this, check the F9 key, F12 key and also try connecting it to a separate monitor(if the monitor works, it's your back light on the laptop). Also try holding the power button for 10 to 20 seconds. ... If none of these fix's work it might be your video card.
I'm going to write Lenovo about sending out an update to fix this issue. Beware, taking apart your laptop voids your warranty.