Hmmm, My new super duper Lowrance GPS/Sonar is freaked out? dead?

Make sure your max depth setting is not 40 feet.
Also make sure you have water between the hull and the transducer.
AND make sure you have enough power going to the unit.
Had similar problems and these were the fixes to resolve them.

I think a water bath will solve the problem. Never liked the goop method. Too hard to get it perfect and keep it that way.