iPhone 6 shuts off when touch ID is connected and cannot turn on

UPDATE: I found out that it's the actually home button that is causing the problem. I will test this theory again by switching the home button with another

Here's a mystery puzzle for all you iPhone repair experts. This might be obvious but I couldn't find any similar situations googling it so I'll ask. I'm not so familiar with iPhones specifically but I dabble in electronics repair so I may be missing something completely that is iPhone specific. Here's the story:

This iPhone was fully submerged in a dirty river for probably 30 seconds to a minute. It was still on when retrieved and I turned it off immediately. I gave it back to the owner of the phone and told her not to turn it on or charge it. She turned it on. It powered on and slowly died. She put it in rice since we are in the boonies with no tools. I thought for sure the phone was a goner.

I got back home the next day and opened it up. I let it dry and it looked clean. It didn't power on. I tried multiple screens and batteries to no avail. I tried different things for 4 days straight and all of a sudden, the phone awoke from the dead! I had no idea why or how. I charged the new battery and messed with the phone a bit switched LCD's with another phone since 2 girls fell in the water both with iphone 6's and I am trying to fix both. It seemed like it was random when it would work. Then I noticed something. When I switched LCD's, the phone would restart. Still confused. I looked deeper and realized that when I disconnect the touch ID, the phone won't start or will shut off if connected while on.

What is this? Is this normal? Is it some sort of security measure? The LCD and touch ID are the orginals with that phone. Is it because I tested it on another phone? If it is, that is confirmation as to why I will never use an iPhone along with 500 more reasons.

Please help me knowledgeable people!!!

Thanks