iPhone 7 Boot loop

Hello Guys,

I came across a series of problems with an Iphone I recently purchased.

Well, I repair Iphones, but only the simple stuff.

So i bought this Iphone 7 that had a shattered screen and that was lagging and had an issue with the home button. Homebutton is clicking multiple times when you click it. Except that, it works fine.

I updated to Ios11 and boom...boot loop. I dug around and replaced some ribbon cables, displays, did some recoveries and found out that it would only boot up when I leave the proximity flex unplugged. It will take about 5 minutes to boot, but eventually it comes back to life.

Another thing I discovered is that voice record was not working. I read somewhere that this could indicate a PCB problem.

Next thing was the freezing. It works like a champ and lag free until i try to open an app, does not matter which. It will freeze for a few seconds.

I also found out that the guy i bought it from tried to repair it himself, lost some screws and the flex brackets.

Well, I hope that some of you guys can help me. I really hit a wall here.