Hello my good people
I recently purchased a 1996 Baja 322 twin 502s.
everything worked great on the boat except the volt, temp, oil gauges. I changed the volt gauges but I still couldn’t read the voltage, I reversed the wires, they worked but all the other gauges started going wonky. So when I brought them back to the original way as stated on the info provided by the gauge manufacturer, nothing works anymore, every single switch on my board shorts out and I am not able to open my engine hatch. Going crazy over here, please help

loose or bad ground wire