acer laptop from turing off?

hi, my acer laptop 5040 was very slow and throwing pop ups up so i decided to format it, ever since i tried to format it the laptop got half way throw format and turned it self off!!. i had the power supply in and the laptop will turn straight back on again but with in 3 min its turns off again. now because it got halfway throw for mat it trys to boot up but comes up with some black screen and then turns off.... ive tried another harddrive and another stick of ram... please help......