Last visit to this site for Janine was June 2018.  Doubt you’ll get a response. 

There is a fuse/relay box on the top of the engine, under the plastic engine cowling, which has a starter circuit fuse and relay.  The shift/throttle controller must be in neutral for the relay to energize and send voltage to the starter solenoid during a start request from the ECM.

True!  I will get stereo sorted but for now just need to know how I can start it. Is there a starter main breaker somewhere?

I’ve been fighting a no start problem the last three years.  2017 22mxz.  Hit the start stop button and it turns off the boat fine.  Then it won’t restart without powering down and turning batteries off then back on and then it may or may not work.  Sometimes resetting the software will fix it.  If that doesn’t work I’ll reload the software from the usb flash drive.  I did that today and now when I power up the screens light up for a second then go black.  Then nothing else happens.  The volume wheel control is the only thing lit up.  Everything else is dead.  I looked under the dash and the two power modules red lights are on.  Batteries are new and charged up.

UPDATE:  so took to dealer.  Found an abandoned/removed stereo amp from a former owner had a positive/negative power wires shorting out.  Fixed by taping up and holding them apart.  I need to follow up and remove them completely though.  
Next:  finally get the boat out today on the water, runs great until I use the stereo.  It runs a few minutes then trips the breaker again.  I do that twice and then I reset ignition breaker and then it won’t start.  Starter won’t even try and engage.  From either the start switch or the emergency key switch.   All the boat screens worked but no start.  Is there a breaker for the starter or engine breaker somewhere?