Ok so here's some history on my phone. (sorry if its too much to read i thought i should give as much info as i can so find the best help) i got a iPhone from a friend its a iphone 6 plus and the screen was broken, i bought a new screen and replaced it with no problems, it worked fine for almost a year. My Freind dropped it, screen cracked still worked perfectly fine. Then one day it wasn't charging so i turned it off and tried to turn it back on but it wouldn't the screen would stay black. i thought the battery needed to be replaced and got a new one. I still didn't work. So i left it alone for a while like 2 months. Then i decided to come back to it, put the old screen back on it to see if it would work and the back-light came on but it was real low. i then put the working screen back on it and it came on. i thought it was working and everything was fine but after like 2 hours it froze and cut off and the screen wouldn't come back on. I put a flashlight on the screen on it and saw that it was still on but like the back-light i guess, the light in the screen was very very low. So i ordered a brand new screen. I replaced the screen and it was working i thought. the screen came on and went to the home screen it then shut off. And wouldn't come back on, i unhooked the screen cables and re-hooked them and it showed the battery dead screen. I then put everything back in place and closed the phone and it wont show the battery dead screen or come on at all anymore. if i plug it into the computer it doesn't recognize it but the phone would sometimes warm up where the screen connections are. Right now if it take the screen out and put it back on it would show dead battery screen then go out again. I don't know what could be wrong with it.