I was able to resolve my issue:
1). plug in your One as if you are charging it.
2). press & hold the button down for about 20-25 seconds to reset your One, while it's plugged in.
3). unplugged your One then press the button to turn it on.
4). go to the Fitbit app and add your device again. your phone should now recognize your One. as if installing it for the first time.
Hope this helps. I had to do this steps a couple times before I got it to work.
Good luck...
Hello @keemohg the reason the user is requested to press and hold the button is that as a new unit, Fitbit assumed that the unit is turned off, and the press and hold is the on switch. If setting up a Fitbit One that already is turned on, there is no reason to press and hold.
And the timer, this is your exercise recording mode.
Best Answer