This may help
Ok so I had the same problem as you all with gear fit constantly rebooting. Here is how I resolved it:
1) Download KIES (It is a sumsung app which you can use to update the firmware on the gear fit)
2) Once dowloaded, you need to get a cable to attach the end of the charger to a USB port on the computer
3) When the gear fit says "Rebooting" on the bottom of the screen. Press the button 5 times.
4) It should then give you 2 options. Continue and Dowload. press the button one to scroll down to "DOWNLOAD" then press and hold the button for 3 seconds. A screen will come up saying the fit is downloading.
5) Open KIES.
6) In the tools menu go to firmware upgrade and initialization
7) Follow the steps. It will ask you for information on the back of the gear fit.
8) Connect the gear fit to the computer when KIES asks you to.
9) It will then download the firmware and you should be good to go.
Hope this helps