Change the oils first
Remove motor and all electric from frame...dry out wiring harnesses and clean with a good electronic cleaner all connections
Submerge frame in a Salt-X solution mixed with fresh water...this will dilute any and all salt in frame. You can use this mixed solution on all parts to dissolve the salt. Wash all parts with warm soapy water and dry thoroughly.
have don this with many submerged outboard boat motors with good success.