Yep, probably control board. Motor steering. Had one of those go out in my older co-pilot controlled powerdrive. Exactly as described. A relay latched or something down inside the epoxy.
Just replaced the power-board on my new Riptide also. No power up. They added a new "automatic power down" circuit for when the unit is stowed. Unfortunately, it wouldn't power back up. And , no, it was not the magnetic reed switch. By-passed that straight away. Good thing these babies come with a 3 year warranty that's extend-able by two more years.