That screen is a sign that your SSD holding Roon and the Roon Operating System is failing. It will need to be replaced.
I see that your Nucleus is now outside of the 2-year warranty period, so your best approach would be to purchase a new SSD to replace the existing SSD and install ROCK onto it. Start from step #3 in this guide:
Note that you’ll need to plug in a keyboard into the Nucleus to boot from USB.
Once you are up and running again, contact @support and they will arrange to have the ROCK version of Roon OS replaced with the Nucleus version - they can do this remotely.