Ideally, an owner should have made a copy of the settings file, after any firmware upgrade. That file could be reloaded after a repair or replacement.
If that did not happen after firmware upgrading, then . . if the owner can access the settings page (buttons 7 and 8 simultaneously), he/she can copy the current settings file. If the settings page is not accessible, then Dynon may be able to copy the settings file at their shop, then reload that file to the repaired/replaced unit. That is not guaranteed, but they have more powerful software tools to deal with anomalies.
When Dynon does perform a repair, every attempt is made to preserve settings and data on the unit. That has been my experience whenever I sent a unit to them.