Is that the only problem you're having? I have the same specs as you and my screen shuts off. I followed the setup perfectly I believe. Did you also use the no nvidia and ssdt4 for the 2450 processor?
i used only ssd i replaced it with sad in extra only
i followed the instructions from a to z but i have a problem with trackpad
it works normally but the problem is that there is a small viberation when i am trying to select an item or exit from application .....etc
generally when i am trying to press
i5 2450
4gb ram
500 gb hard