Found this info on another Fitbit thread by MaryGail64 and it worked for me! My Fitbit is back up and running!🎉🎉
”Press and hold down the side button for about 8 seconds until the screen turns off. After the screen turns off, you feel a short vibration, lift your finger off button two second (do not let the logo light pop up ) then immediately press and hold the button again, Wait until the watch vibrates, lift your finger off the button again for two seconds and press it down once more until you feel one final vibration, then release–this indicates your Fitbit is performing a factory reset. once it is done wait about five mins if it is black that means it worked, tap your watch if nothing shows then press the button, if you see an RED X , check your phone or web page which ever device you keep track of your fitbit watch , you should see a pop wanting to connect with your watch accept it and go from there , everything should start getting redownload and updates.”
