I'm having trouble with this as well. I've only had my Fitbit for 2 years but the screen has become so dark it's unreadable.
You can try to swipe to Settings on your device, then click Brightness and toggle between modes. This doesn't work for mine. I'm trying to chat with support now.
Best AnswerI am having the same problem, but my screen is so dark I cannot even tell when I get to settings. What do I do now??
Best Answer