that model is discountinued...lowrance sometimes will not repair them..they offer a upgrade...to a newer model...your unit and cash for a newer model....
....A loose contact does strange things,,,,I know...lol.....make sure the the connections are clean...the power plug..the transducer and the GPS puck if u have one....wipe connectors with alcohol plug them in and make sure the connection is tight
Al
hope it worked out for you.....I had the same problem....and the cleaning did it....good luck and tight lines
Semper Fi
Al