Help df225 60amp fuse blowing

[Dhemmerly]

I have a df225 that is slowly blowing the 60amp fuse. Boat was brought to the dealer but they could not diagnose the problem. Only suggested throwing money at it as in replacing the wiring harness and replacing the ecu with no gurantees to solve the problem. Any other suggestions would be greatly appreciated. Anyways the fuse takes 1-2 trips before it actually blows. All terminals positive and negative on batteries and engine have been checked cleaned and checked again as well as visually inspecting the wiring harness for and corrosion. At idle the fuse varies between being warm to the touch to extremely hot where it will burn your finger tips. Fuse will begin to char throughout the day until it eventually blows. Any suggestions as the what to check next? How hot should the ecu get?