Sorry to hear about the trouble, @Kfab. If you're still encountering any issues, you can get in touch with WooCommerce Support directly. Hope this helps clear things up. Please let us know if we can help with anything else.

Hey @Kfab, if you purchased the official WooCommerce Square plugin from WooCommerce.com, then you can contact our support team directly at: https://woocommerce.com/my-account/tickets/

If you are using a plugin from a different third-party developer you'll want to contact them directly for help with their plugin.

With our plugin there a few steps I'd recommend checking:

1. Make sure your business location is set. This can be done under the WooCommerce > Settings > Integrations tab
2. Make sure your WooCommerce site is the same currency as your Square account. This can be done under the WooCommerce > Settings tab
3. Try temporarily switching to the Twenty Seventeen theme to see if it's a conflict caused by your theme (I recommend doing this on a staging site and not your live site)
4. Try temporarily disabling all plugins except for WooCommerce and WooCommerce Square, again I recommend doing this on a staging site

you can follow this step by step guide to set up Square for WooCommerce. Let me know if you have questions.