Why won't my cracked G Pad X8.3 respond?

I have an LGVK815 G pad X8.3 tablet with a crack on the screen ,and the screen keep jumping from one page to another without me touching it then when i try to turn it off , press an app or even try to type on my keyboard it won't respond ...and does whatever it wants ....i cant even turn it off or anything. Anyone have any idea why its acting up ?