Login button does not function

There are two common causes for the modal popup to not work properly:
1. The Javascript for the modal may not be included properly on the page. This can occur if there's any compression on the page from your template or from an extension like JCH Optimize. If you have this enabled for your site, please disable temporarily to see if that helps with the behavior.
2. There are options in JFBConnect and SCLogin for Load JQuery. Please try enabling the option in JFBConnect first to see if there is any effect.

Are there any errors on the console? Are there any PHP errors on the page?

This should help to start narrow down the problem, so let us know.

-Melissa

Also recently I updated .htaccess file by using Admin Tools.

This is likely the issue. If you are using 2 factor authentication on your site, you'll need to make sure that the following file is accessible from a browser:
/modules/mod_sclogin/ajax/otpcheck.php

If that file can't be accessed, the check if the user should be shown the Code field can't be checked and the long process will just hang.

I hope that helps,
Alex

To test, just go to:
<Path to your website>/modules/mod_sclogin/ajax/otpcheck.php
If that throws a forbidden, 403 or other error that the page won't load, that means there's a restriction that's preventing a browser from loading the page.

You should see a blank white page with something like:
If you're not getting the right response, you'll need to fix whatever is restricting that page from loading.

Thanks,
Alex