Very low wifi connectivity after housing replacement!

I replaced my iPhone 6 housing with a third party one as it was bent! I followed a YouTube tutorial and I am sure that I did 90% of everything exactly as shown in the tutorial! After replacing and putting every component back to its place, I turned the phone on, every this was working fine but there's a problem with my wifi now, it only works when I sit right next to the router, moving a few steps away results in a loss of connection and when I leave the room, the wifi goes off completely! Please guide me if I did anything wrong while assembling the phone back! Thanks!

Got it fixed today! There was a flex cable with four connectors underneeth the MB! One of them was loose! Put it back and wifi is awesome now! Thanks!