Updating the Software of the T300/T500 can only be done online.
Go to: Configuration -> Server - > State
Newer versions to update your software will be listed with:
Prior to the actual update process a backup of the system will be performed. In case of a failure during the update the current state of the system will be recovered without loss of data.
If this setting is enabled, the system will perform a weekly check for a new software version. In case an update is available, the administrator will receive an automated e-mail containing the details of the new version.