Charge 5 won’t sync or reset stats after midnight

[Caylin1803]

My charge 5 still shows the same stats as yesterday. They are continuing to update but only just add on, rather than starting a new day. 
My charge 5 also won’t sync with my phone this morning. I’ve tried a number of times. 

I have used the restart button and held the flat button down on the charger a few times but nothing has changed.

I haven’t travelled - just done my normal everyday routine for the past couple of weeks. 
Any ideas what I can do to fix it? This will mess up my stats. 

[Caylin1803]

Pressing the flat button on the charger 3 times seems to have fixed it, but it has lost all my sleep / O2 / heart rate data from last night in the process, which is quite disappointing.