I contacted Nike for the 3 fuelbands this happened to me (original and 2 replacements), and they replaced all of them for free. Nike said the spring behind the button can become misaligned over time, and it sounded like a common issue. The fuelband continues to track your movement even though it won't display anything, but you'll have to plug it into a computer to sync your data before restoring it and setting up the new one. Hopefully V2 has fixed this issue.