Why did my android phone stop working?

[Android Central Question]

So I was Facetiming a friend, and then my phone started to lag a bit. I didn't think anything of it, and then the screen just turned off... I've tried everything I can think of, but I just can't get it working again. There have been no previous issues with it, so it's really weird... I have a OnePlus 3. Any help would be greatly appreciated...

 

[belodion]

What have you tried?