You can try a firmware downgrade, but you need to know what firmware you have at the moment, what the model is of your particular RNS, and what firmware it originally had ideally. Then you can go back to the start and load on the factory firmware it should have. That would give you the best chance of sorting it.
To downgrade the firmware you need access to the secret (developer) menu which you don't have. Throwing firmware cds at it in an attempt to fix a firmware issue will likely end in tears, or just plain failure.