Glad you got the problem worked out. You are not alone in this frustrating scenario. The takeaway from this are cheap lessons learned for all fellow Tugnutters (all boat owners for that matter), particularly to folks relatively new to the game. First, take a deep breath (if your not sinking) and think about the issue as part of a system. In other words, troubleshoot from a cause and effect standpoint...did you just throw a switch and the system reacted improperly? Then, start by eliminating common causes (tripped CBs, blown fuses, loose grounding wires, clogged filters, loose clamps, malfunction codes). The chances are good that you will find the problem and the fix will be relatively easy.
Here are two examples we experienced (and there are a bunch more):
Main engine would not restart at the gas dock. OK, the symptom was the starter would not turn over engine. Batteries good, electrical connections to starter good. Using a multi-meter, we found a power loss at the ground terminal to the engine bell housing. We disconnected, cleaned corrosion and reattached. Engine started normally.
I noticed a significant loss of water in the tank an hour after leaving port with the tank full. OK, that's the symptom but where did the water go? I turned off the water pump at the breaker, opened engine hatch to inspect the bilge (where the water would go, ha) and found a cascade of water flowing down the port side. What water source is located there, the water heater, dummy. Open up port side gull wing and notice a hose popped off said water heater which was reattached and double clamped. Problem solved.
So, if not in extremis, take a deep breath, get some more coffee and think of the affected system(s). Use diagrams either provided by Ranger Tugs or self-made. Get a multi-meter, fix that loose wire, blown fuse, tripped cb, etc. This technique has served us well and was formed over 45 yrs. of boating and 33 yrs. of flying airplanes.
A call to Andrew can help too when all else fails.
Have fun and be safe!
//Bud