Twice, so far, I've been unable to turn my Kindle Fire on. This is while the battery still has a pretty good charge left, mind you. No matter how much I press the button (or press and hold it for a couple seconds), it never comes on. I usually have to wait 10-15 minutes, and then try again, and it'll start up normally. This second time, it even turned on by itself about ten minutes after I had pressed the button a bunch of times.