Windows 8 lenovo laptop blacl screen? - 1

My windows 8 lenovo laptop u510 the screen is really dim when i put my flash light on the screen i can see that yhe screen is not completely black also it shows that the brightness is max how ever the screen is black when i don't flash my light in it, My laptop isn't upgraded to windows 8.1 yet but i'm upgradig it righy now in case the black screen has anything to do with the upgrade please help would be appreciated, thank you