iPhone 5s screen lightup

Dear ifixit'rs,

Yesterday i bought a broken iphone5s with a broken screen i hoped i could fixed it with a new screen because the screen was just lighting up, taught the screen was damaged, now i put a new screen on it and it has the same problem when i boot the iphone the screen ligths a little bit up but i cannot see anything, i dont see the logo or the ios just a little backlight; so the iphone is trying to boot , is this a software or hardware problem