Charge 5 will not create an exercise session

[Deipnosophista]

My Charge 5 will not create an exercise session, and the Settings function will not open. 

The advice on this seems to be to close it down by pressing a button on the flat side of the charging cradle (the expectation presumably being that restarting it will solve the problem).  I have three charging cradles which charge perfectly well, but none of them has a flat side or a button on it.
The alternative advice seems to be to connect the charger and then turn it off for one second, repeating this three times.  It is not easy to turn it off for precisely one second, as (i) a second is very short and (ii) the process involves either disengaging/re-engaging the Fitbit from/to the charging cradle, or unplugging/replugging the cradle's power supply connection, which are both slightly fiddly.  I have tried this process three times with slight variations, and it has failed. 

What now?

[LZeeW]

Hello @Deipnosophista and welcome to the Community.  Here is a link to Fitbit's Help article with the relevant section expanded for you.  Your Charge 5 and my Luxe use the same charger.  I used the, "one, one thousand, two, one thousand" method to time my button presses.

Please take a look at my link.  It might give you visual help to re-start your Charge 5.