Do you have a younger one at home? Here's another way you can use guided access...

"There comes a time in your life when you must hand your beloved smartphone over to the slimy fingers of a young child who has asked to play Zombie Farm.

And while you may not have any control over whether your phone is sneezed on, buried in sand or dropped, you can at the very least make sure the little beast isn’t running up your Candy Crush tab or texting gibberish to your crush." -Alyssa Bereznak  

Here’s how you lock the screen of your iPhone using guided access so it functions in one app and one app only.

https://www.yahoo.com/tech/heres-how-to-lock-your-iphone-so-it-wont-run-anything-74100463523.html