The FB Connect button has been wonky for at least two weeks now. You can click it or open it in a new tab and it does nothing. Leaving some of the people who use that unable to log in. I found a workaround for people to still get through.
Go to the "forgot your password" page. Use the email that your Facebook also uses. With that you should get an email with instructions on how to change everything. After you do all of that, sign in with your username and new password and boom. You can sign in through normal means instead of using Facebook. I'm not sure if you can switch that back afterwards, I guess we'll have to see when it's working again. But for now, that's your way.