Hi Carl,
I must admit, I'm at a loss here. Did you use the iFixit [guide|31738|iPhone 6 LCD and Digitizer Replacement guide|new_window=true]? If so, I see nothing there that should have any effect on the wifi or bluetooth signals; not even close.
Maybe a little history on the phone would help. Why did you replace the screen? Are you sure the wireless signals were working between whatever happened to the display and when you replaced it? I'm curious as to whether it was the original damage or the repair when the wireless quit working.