Multiple switches turn the stereo on, and they do not turn the intended accessory on

[CFD3Captain]

I am getting the boat ready to sell and just got out of storage. Hooked the batteries back up and went to run the stereo and got nothing. Once I figured out the headunit was off, the stereo worked, however if I try to turn on the blower, nav lights, or docking lights the stereo stays on but the light on the switch goes out.. ALSO if the stereo switch if off, those three switches will turn the stereo on. The main breakers are not tripped and both have been reset. Obviously those switches are not turning the intended accessory they are hooked to on. Any ideas? It was all working find end of the year :(

[MLA]

Hooked the batteries back up

Id circle back to here. This time of year, this where a lot of these issue arise. Mis-connected or left off cable.

[zabooda]

Bad ground. Some of the components are grounded together however there is a bad ground between them and the battery that allows a back flow through another resistive component like the bilge pump or a ground on the indicator light where the voltage on both sides of the light would be close to 12 volts thus no flow through the light.

[zabooda]

Did you get the problem fixed?

[hymanykd]

Did you get the problem fixed?
I have 2014 Mondo and exactly the same thing. Checked the breakers both at the battery and main motor as well as the ones under the dash. Cleaned the battery negative post plus the ground plate terminals. Is there any other common ground plates? Or location of common grounds? Any help would be great!