Last night my EVO went unresponsive. I had used it earlier in the day without any issues. I didn't get a chance to check it all afternoon, and by 10pm, it was dead. I tried to plug it in with the wall charger, but I couldn't even get the LED to light up. This morning, same thing - won't turn on, no LED, no signs of life at all.
It's still stock - I haven't rooted it. I did notice that in the last couple of days, some apps weren't responding, and I would get the "loading" circle when I tried to go back to the home screen. No idea if this is related.
Perhaps I posted too soon. I held down the power button for a good 30 seconds, then touched the home button. The phone sprang to life, booted as normal. Very strange.