Hi! Sorry to hear you're having issues charging.
First, can you try unplug and replug the charger cord?
This should work to get the devices charging, but if not, I suggest trying to reset the wristband.
To do this, go to the account tab, click on your wrist band and scroll down to where it says reset.
If that doesn't work, try uninstalling and reinstalling the app.
You may get a notice saying all info will be deleted when uninstalling but when you sign back in your information will repopulate.
Let me know if that works 😊