Start button not working
As much as it sounds bad, try spraying wd-40 in the start button with everything off, let it sit out in the sun for a few hours to let it soak in to the metal contacts under the switch and to dry out the wd-40. Then after say 4-5 hours, go out there and press the button a good few number of times say 100 pressing fast and hard a couple of times, that way if rust is on the contacts the wd should free some of the rust up and knock it loose off the contact.
Next time you go to wash bike put a plastic bag over the button to keep out the water and just wash around the area with a damp rag rather than soaking the whole area, should help to keep the button dry.
Worse case scenario is you can get a new/used button on ebay, replace and then start using a plastic bag to keep dry. those things are rough when the switches get wet on a bike.
Hope this helps.