My iPhone 6s Plus has a mind of its own while charging. It will open apps and actually send messages. What's wrong with it?

My iPhone 6s Plus has a mind of its own while charging. It will open apps and actually send messages. What's wrong with it?

I'd restore iOS.

That's weird, it could be water damage or a hack; but hacks are very improbable unless you have jailbroken the phone.

You normally can solve some computer and electronics problems by totally turning them all the off and then on again.