Background: Operated mower for a couple hours and washed it after it had cooled. Then I started unit and moved into sun to dry.

Symptom: After a couple hours of drying I tried to start the unit. The starter engaged momentarily and then the unit shut down - now it will not engage. Voltage is 12v, fuses and fusible link are OK, guages read properly, relay "chatters", fuel pump runs. Note: PTO is not engaged and the brake is set, What am I missing?

Thanks!

I would would remove and reconnect my battery connections,
Just because you have 12 volts doesn't mean there's 12 volts coming out.check your ground on the engine.water could have got between the connections and croded doesn't take long.check under the top of your dash the control module is under that check plug on this put some electrical grease on it .
Luck