Black screen after replacement

Hello, I've bought a repair kit + screen for iphone 7 last week. I’ve strictly followed the guide and took all precautious measures.

My phone turns out correctly and pair with my bluetooth devices correctly, however the screen remains black (not a backlight issue, I’ve checked with a torch + works with previous screen)….the home button still works.

Whenever I put my old screen back, stripes of colored lines (this is why I replaced it) are displayed…bluetooth devices pair as well.

Any help much appreciated, It feels like the screen I’m trying to plug is just malfunctionning…