There are different reasons for all of those things to not work individually, but with all of them happening at once on something that has been sitting for that long with water getting it I would look at the wiring itself, you might have had rodents or water corrosion somewhere. It could be really hard to find too.
Best you can do is start testing for power and resistances in different places to try and diagnose. Wiring stuff can be a real pain.
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