It took me hours and finally figure out what went wrong after install cheap GoDaddy SSL on shared IP on VPS at Hostgator.
Issues: I bought the SSL certification and install on my VPS, which already have 2 dedicated IP (2 other SSL already installed). So my only option is to install the new SSL on the shared IP. While install the SSL, WHM tells me to install the SSL as nobody due to the IP is shared IP.
After restarting the Apache after installing the SSL, the HTTPS works fine on any file that is NOT PHP. When I load the WordPress, it shows me the 500 server error.
It took me hours to figure the Shared SSL with nobody user group is conflicting with suPHP due to the permission.
The idea of fixing this is to assign the SSL certification from nobody to the right cpanel user that owns the add-on/parked domain name. So here are the steps: