4th Generation Kindle wouldn’t boot up. When I pressed the power button the green light would come on… then go off, with no action on the screen at all. I had tried holding down the button for 15-20 seconds and all that happened was the green light flashed 3 times (as it does when you’re powering down) and that was it. After reading this feed, and the comments, I kept the button held down for 30 seconds and nothing appeared to happen but after approximately another 30 seconds the screen came on and it started doing a reboot. THANK YOU EVERYONE! I’m overjoyed it’s working again!