iPhone 6 Keeps Shutting Off After Replacing the WiFi Antenna

I bought this phone off a women on letgo only a couple months ago. When I first got it the battery didn't last very long so I bought a new battery and put it in myself no problem. The phone worked fine for a couple months then my wifi would consistently drop. So after trying everything online about how to fix that I just ordered a new Wifi/Gps antenna. I installed that myself only a couple hours ago and after putting everything back together the phone boots up and I can unlock it any everything just fine then after maybe a minute the phone just goes to the apple logo and reboots. While it shows the apple logo the screen goes black for about a second then continues to reboot itself. I bought this battery off ifixit almost a month ago the battery shouldn't be bad. Any thoughts on what I can do please?