log into cPanel, find the Logs section and click on Error logs, see what it has in there.. Most 500 errors will make an entry into that log telling you what caused it.
If it's a permission error, try this as well. Most times it's not an htaccess error, but instead it's this:
You need to login to your cPanel.
http://yourname.x10hosting.com:2082 and go into the File Manager, select the files in which you'll be accessing on the website and click on the Permissions button at the top of the page. The permissions need to be set to atleast read execute, and write if the page is going to be making any dynamic changes to the site. Usually read/execute is enough to get it working.