iPhone 6s unresponsive display when unlocked
I had a similar problem. It occurred after iphone music app became stuk while loading. Phone wouldn't turn off and wouldn't respond to swipe or changeing the app. 
I pressed down simultaneously on the home button and the off button on the side . After awhile the phone shut down and the slider bar appeared and I was able to shut the phone off. Than able to turn it on and things are working now.