To reset the clock to factory settings, please hold down the lower button and press the middle button three times in quick succession. The clock will now ask you if you really want to reset. Therefor press the lower button (where the checkmark appears). You can now connect the clock to a mobile device.
First, you should make sure that both the Bluetooth function and the location services are enabled on your mobile device. You should also make sure that you have downloaded at least the latest app version and the latest operating system version from your smartphone provider.
If the above points apply and there is still no way to connect the clock, make sure that the clock is not/was not already connected to another device. If this is the case, please remove the clock from your Bluetooth device list and from the Oskron App. To do this, click on "Device" in the app and then on "Forget this watch".
If you cannot register, you should try two different ways:
Try to register in the app while there is an active WiFi connection.
If this does not work, try registering while you have an active Internet connection via your mobile data.