Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Are you getting battery voltage to the switch terminal on the starter solenoid when start is selected? Or you get no battery voltage to the main switch?
If the switch terminal at the starter solenoid gets voltage, the solenoid would not be closing. If you jump the battery cable terminal on the starter solenoid, to the switch terminal on the same solenoid, does engine crank?
What is battery voltage? Should be above 13 volts if fully charged!
I gather you don't have a voltmeter to test with. With no knowledge to check the unit, I would find a professional to check the unit. Replacing an engine controller is high priced trouble shooting, just to find out that battery may be dead.