You can place Stryd on the charger. If the light comes on, Stryd is charging. Charging will complete in a few hours. If the light switches off, Stryd is fully charged and you are ready to run.
You can use the Stryd app on your phone to check the level of the battery. Note that the battery gauge in the app is not very accurate.
For iOS, go to Settings and look at the battery level icon.
For Android, you need to start a run. Select Start Training and activate your Stryd by shaking it vigorously. Once the phone detect your Stryd, you will see the battery gauge top right:
Contact email@example.com if you experience any problems charging your Stryd.