Try installing a fresh copy of WordPress. If that works, the clone mainly fails due to server memory limitation or PHP / Webserver timeout.
Try uploading the backup file to your server http://yourserver.com/ and use the link to your backup file http://yourserver.com/backupfile.zip. It reduces the downloading time of the backup.
Increasing memory limit of the destination server would help resolve 500 error / memory exhaust error.
If the clone appears to be incomplete kindly increase the PHP / Webserver timeout of the clone.