Oliver Davies

I recently replaced the rear housing of my iphone 8 plus and I now have really bad reception compared to other iphone 8...

I had a look and one of the bracket connectors had snapped, so I replaced that and it’s working beautifully

You most likely dislodged the touch connector. Easy fix, but you will need to tools to open the phone, disconnect the battery connector (always do this first), and then disconnect and reconnect the screen connector tabs. Here is the iFixit guide: Reemplazo de pantalla de iPhone X Complete up to step 20 then do everything in reverse.

Unfortunately you cannot put any iPhone's motherboard into another iPhone and have it work. They are not interchangeable.