Can you tell us more about what version you are upgrading too? The last subscription I see for your account expired in October. The latest release at that time was JFBConnect v6.2.2. Looking at the
changelog
since that release, there have been a number of new features, but nothing that's specific to login issues. As always, of course, we recommend using the latest version which is currently v6.4.0.
Please let us know what version you're using, and what account you used for the subscription, so we can look up any details about your site that have gone through Autotune.
Also, please let us know what specific issue you're running into when you say "login button is not working". Is it a specific social network, the Joomla login button, or something else?
Thanks,
Alex