So I had the same problem, I replaced the screen it was working fine till i put the phone all together then the phone died. I have left the phone without the battery and screen connected. What I have find out that the electric statics killed the batteries as there was still power in the phone and after the phone got rid of all the electric power inside I have placed new battery and new screen and it works. I don't know if that would work with everybody but it worked in my case.