I'm unsure what's happening. When our Autotune tool tries to contact your server, it's responding with:
[code]HTTP/1.1 502 Bad Gateway
Server: nginx
Date: Sun, 27 Jul 2014 23:27:38 GMT
Content-Type: text/html
Content-Length: 166
Connection: keep-alive
<html>
<head><title>502 Bad Gateway</title></head>
<body bgcolor="white">
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx</center>
</body>
</html>
That's a response coming from your server, not an error on your end. I'm not sure why it's throwing that though. Your access logs may shed some light on that, if you want to investigate further.
As for the issues the tool would have found, they are:
1) The JFBCSystem plugin is not enabled. I'm assuming you haven't done that yet since you couldn't run the error checker
2) You're using a Gavick template and have their social login feature enabled for Facebook. That should be disabled or it will cause plenty of problems with all of our Facebook integration.
I hope that helps get you going, but if you run into any other issues, just let me know.
Thanks,
Alex