If you have a valid support contract you can download the DoT software in case the system does not like teaching you about NetApp SANs. There is also a NetApp simulator available for download so you can try before you break your FAS2020. Just search here for simulator for details.
To run setup again, reboot your filer with a serial cable terminal session. Ctrl-C to get into the start up menu and happy days. The DoT software is on both the disks and CF card if you want to risk running setup again but high risk.
Recommend you learn more first or at least call NetApp support.