I have a humminbird helix 5 si that I purchased in March 2015. We fished all day Saturday and unit worked fine. Sunday the first wave we hit after leaving the marina the unit lost power. First thing I did was check and clean all the power connections to battery. They all looked good. Replaced the inline fuse. Made sure the power cord was secure in unit. None of this fixed the problem. After that I unplugged the transducer cable and ran the unit in simulator mode to see if it would still power off when the boat hit a wave. Did the same thing in simulator mode. After that I restored factory defaults and that did not fix the problem either. Last night when we got to the house I plugged the unit in while sitting in the drive way. In the dark the unit has a constant on/off flicker of light as soon as you plug the power cord in. I'm almost positive there is an electrical issue inside the unit. I'm not sure there are any other parts I can check but I am open to any suggestions. I have no idea what the warranty on this unit is, but I'm sure hoping that it is still in warranty. Only had it for three months.