iPhone 8 is freezing up

So, I was using my iPhone X this morning when out of nowhere, the whole thing just froze up. It was a nightmare trying to shut it down, and once it finally did, getting it back on was an uphill battle. After a bit, it froze again and just died... now, it won't turn on at all, and it refuses to take a charge—plus, the device feels totally cold to the touch. The battery was sitting at 90% earlier today, so I'm assuming it's not a dead cell issue..

Any idea what might be causing this?

I've got an iPhone 8—totally messed up the thread title..