Endless loading/spinner on the woocommerce checkout page - ajax

Question

Since some recent updates , the checkout page on my site is not working. Even after entering name/address, the area under “Your order” is greyed out and spinning.
Things I’ve tried that didn’t work:
Disabled all plugins (except woocommerce)
Changed theme to Default theme.
Checked Woocommerce>System Status.
Increased memory limit via wp-config Disabled PayPal (the only payment gateway)
Removed the woocommerce files via admin and
uploaded a fresh version via FTP
Checked items on this page: http://docs.woothemes.com/document/endless-
loadingspinner-on-the-checkout-page/
I'm runngin NGINX 1.6.3 server and seems to be no issue with server as other woocommerce sites on same server works fine.
I’ve looked at the Chrome console and found this:
https://example.com/?wc-ajax=get_refreshed_fragments Failed to load resource: the server responded with a status of 405 (Not Allowed)
I checked using full URL like https://example.com/index.php?wc-ajax=get_refreshed_fragments and it shows some ajax code but using https://example.com/?wc-ajax=get_refreshed_fragments shows homepage.
Disabling Ajax completely on checkout page works but it does not update price for checkout addons like gift wrap.
This is config for my site:
server {
listen 80;
server_name example.com www.example.com;
return 301 https://$server_name$request_uri;
}
server {
listen 443 ssl spdy;
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
server_name example.com www.example.com;
root /home/user/example.com/public/;
index index.php;
access_log /home/user/example.com/logs/access.log;
error_log /home/user/example.com/logs/error.log;
location / {
try_files $uri $uri/ /index.php?$args;
}
location ~ /.well-known {
allow all;
}
location ~ \.php$ {
try_files $uri =404;
fastcgi_pass 127.0.0.1:9000;
# With php5-fpm: fastcgi_pass
#unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
}