Hi Paul,
The cron alerts that you are getting every hour are just one symptom of the upgrade failure that is visible. There may be other issues with the system that are not visible or obvious that may prevent further upgrads or cause other problems later on.
If you call support, they may be able to assist you in removing the duplicate cron job, but most likely they will also advise you against using the appliance in the current state after a failed upgrade.
As for the OSRESTORE CD, you can download the ISO image from Symantec FileConnect website and burn a CD. Yes, you will have to create the settings from scratch after an OSRESTORE unless you had a good backup and restore data from the backup, but if you take a backup now, I won't consider it clean and reliable due to the current state of the appliance.
Regards,
Adnan