Electronics Technician: Dr. Fix-It. Hi, please push/slide the power button and HOLD it for a full minute. Then let go, and wait until the Kindle resets and reboot. If the Kindle doesn't reset on its own, push the power button for 2 seconds and let go. It will now function normally. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.