I guess if it were me I would pull the dash and disconnect/reconnect the harness that is going to the screen, and the connection at the brain box (medallion?) under the dash. Also check the bus bar under the dash and make sure all the ground screws are tight. Since it sounds like it is just a canbus communication issue that is not impacting the ECU itself (since the boat runs).
In my 2012 I have an issue with my upper screen every once in a while that requires the connector be plugged and unplugged, although in that case it is just the RCA cable from the brain box.