Try Odin mode on samsung gear fit 2 to reload firmware/software. 

I had a Samsung Gear Fit 2 Pro that was rebooting. I put it in Odin mode to charge it up and re-flash the firmware/software. The watch seemed stable in Odin mode, so I was able to charge it up by going into download(wireless) mode. The display remains on in this mode and it shows the battery level. I was able to fully charge and reload firmware/software to ensure that there was no corrupt files causing the problem.
NetOdin 3 and firmware links I used can be found here:
forum.xda-deve...