[lamb]

You've got to make sure the power / battery is up to snuff. Try to see if you get a same thing with a different battery.

In my experience, transducer going bad is most often the reason for symptoms you described. The easiest thing to do to troubleshoot is to try your fishfinder on someone else's kayak. Sure thing, assumption here is that they have the same or model compatible with that transducer. Alternatively, you can try plugging in their fishfinder to your transducer.

Other than cleaning the connectors on both ends, there's not much you can do to fix a transducer. I've been just replacing them.