I had an Eagle 480 Fishfinder installed (single frequency). It was working fine when first installed but when I took it to the lake for the first time it worked fine for about two hours and then the depth screen froze on 22ft. I cut it off and back on but now shows 0.0ft flashing (depth not working) and the fish finder does not work (screen not scrolling) but temp appears to be working. I thought it was problem with this fish finder so I had it took off and exchanged for another one and had it installed. I have the same exact problem, worked well when first installed. Took it to the lake and it worked well for about two hours but then it froze on 11ft, cut off and on and now on 0.0ft flashing and fishfinder not work (screen not scrolling). Still under warranty so can take back, but does anyone have any idea what is happening? I am concerned it may not be the depth finding but something going wrong in the install given I had the exact same problem twice. I have to pay labor every time I change out so would like to understand if there is something wrong with the fishfinder or installation, any suggestions will be greatly appreciated.

GPS - Eagle - FishElite 480 Sonar/GPS Mapping Combo GPS Receiver