Loss of touchscreen ability with iPhone case

Hi, I’ve had an iPhone 6 for years now and I’ve always had it in a lifeproof fre styles case and have gone through many cases with no issues whatsoever with the touchscreen interface. Even when dirt and sawdust gets inside. However today the touchscreen ability suddenly stopped and I couldn’t punch in the access code or touch on icons. I took it out of the case and it worked fine. Put it back in the case and it doesn’t work. Put it in a new case and it doesn’t work again. Put it in some other older cases I have lying around and again doesn’t work. It will work however when I put on only the front of the case but when I put the back on doesn’t work. Not sure if that is some weird grounding issue? Even put a little piece of wire into the case touching the back and sticking out so I can “ground it out”. Still didn’t work.

Also tried the obvious things: turning it off and on a bunch of times, trying to adjust the sensitivity (though the phone doesn’t have 3D Touch so there isn’t much to do), I don’t know, I’m stumped. Still really like the phone and don’t feel like replacing it. Not sure if replacing the screen would help? I’d welcome any ideas. thanks!!