Why did it quit after the June 14 upgrade?

I updated on June 14, 2017 and my watch stopped working. That entire evening, it would flash the opening power-up screen, following by a rebooting message. It did this for about 10 hours and I powered it off when it became too warm. Now, it won't power up at all and when I put it on the charger, it only shows a lightning bolt and the green circle. Ideas?