When you have an unexpected redirect loop error (“domain.com redirected you too many times”) or 500 error:
1. For WordPress users, this is usually caused by incorrect file/folder permissions. This should be 755 for all folders and sub-folders. It should be 644 for all files. For information on how to set permissions see this guide
2. The redirect loop or the 500 error can also be caused by corrupted files after using cPanel to unzip the files. Try to extract (unzip) the files locally and then transfer them via FTP software in an uncompressed form.