iPhone completely unresponsive: Doesn't charge, Unrecognized in iTunes

After working without issue for about 8 months, yesterday my iPhone 6 turned itself off. The phone was almost a full charge, around 90%.

I left it in my pocket for a while and when I reached for it about 15 minutes later, it was very hot. I left it alone longer until it cooled down and then I attempted to google the issue because it was not responsive. I tried many forced resets, plugging it into iTunes, DFU mode, etc. etc. Nothing has happened.

Today, the iPhone is completely unresponsive. I've tried different chargers, different plugs, different computers, and holding down every combination of buttons on the phone possible. Anything I can do myself before giving in and going to Apple?