I had the same problem. The green lights stopped flashing and stayed on constantly, which emptied the battery very fast. The heart rate monitor did not work properly. Charging the battery did not solve the problem. Stopping the lights/heart rate monitor may solve the issue but I want to keep the heart rate monitoring. I left my Fitbit unused for a week. Then charged it again. The Fitbit worked again like before but it only lasted for 2 weeks. The same problem with the constant green lights and heart rate monitoring not working came again. I also noticed that around the time of the problem, the sleep stages could not be identified which may reflect the issue with the heart rate monitoring. I will contact Fitbit as it seems the device is defective. And there are a few if not many who got the same problem according to forums.
