Alienware black screen

my X17 alienware laptop is giving me hard time ever time i put it to sleep or reboot the screen goes black and after moving the screen many time up and down it turn on again this what i recognize

every time i put the laptop to sleep or reboot i have a black screen

at the beginning when i move the screen this solve the problem and it turn on then after a while this no longer solve the problem then i noted that when i remove the power jack the screen turn on then after a while this didn't solve the problem and any of this two way manege to turn the screen on again then i recognize that when i remove the power jack and start moving the screen it turn on and after many adjusting it turn on and stay on now i recognize that  no longer help the screen goes black even if am doing nothing on the laptop and give me hard time trying turning it on again BTW when the screen is black and i connect the laptop to external monitor every thing is great on the external monitor but the lap screen is black this very frustrating my 4000 $ laptop is doing so after 6 months my sony vaio laptop screen  is attached to the lap from one side only and it is working as brand new ..... i begin thinking that it was the worst decisions i had ever made buying alienware laptop any way does any one have any solution to this problem or know why my laptop is doing so plzzzzzz