Another solution: I had a similar problem during an iPhone X repair. When I clicked / pressed the screen into place, the phone shut off. I noticed that the edge of the battery was scratched. The black covering had scratched/peeled slightly, revealing some metal. And I theorized that pressing the screen near that area was causing the problem. I covered the scratch with a piece of electrical tape and it solved the problem.

6 month update — buy from ifixit.com NOT Amazon!

I had weak wifi signal strength and the GPS was not accurate (blue dot on Google maps was always wrong or would not track my location). So I bought the antenna flex cable from Amazon (brand is called MMOBIEL WIFI sold by Menko Teleco). I followed this repair guide but found no improvement to wifi/gps.

After 6 months it became unbearable so I bought another cable, this time from ifixit.com, and did the repair again. Now everything works flawlessly.

This time I noticed that the cable from Amazon was missing the blue sticker shown in the picture. The ifixit cable had it. So maybe it’s important.

Anyways, I can confirm this repair works, but make sure to buy the cable from ifixit.com