As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WATER FROM WASHING THE AIRCRAFT WENT DOWN LEFT SIDE WINDOW INTO SWITCH PANEL CAUSING MASTER SWITCH TO ACTIVATE MASTER SOLENOID (WHEN IN OFF POSITION). THE WATER FROM WASHING ALSO CAUSED LT ENGINE STARTER SWITCH TO ACTIVATE STARTER SPINNING PROPELLER (WHEN IN OFF POSITION) NOTE: PROP STARTED TO SPIN ABOUT 1 HOUR AFTER WASHING.