Hello, @zooster,
Yes, that is because you made a mistake, Please Login to your WP and then delete the XStore Core plugin, after that, you have to update the theme first to the very latest version and then after that Install the XStore Core plugin again and I am sure it will solve your issue, Otherwise please share your site WP Admin URL and Credentials with me, in the private content area of this topic, as listed below, so that I will check it for you on your site and help you out.
And please note that, always first update the theme and then update the core plugin to avoid this kind of issues in future again.
Regards 8Themes Team.