Small Engine Troubleshooting Problems? Ask a Mechanic Now.
You say it won't turn over? Have you checked the fuses? When the solenoid came apart, it could have blew the fuse, and now you have no voltage to the key switch.
Does the shutoff solenoid open when you turn on the key? Do you get any indication that the key has voltage? If not, fuse or fuse holder is suspect!
OK< fuses are good! The relay you mentioned , shows to be start relay, it could keep engine fro engaging the starter. Do your glow plugs show to be working. they use a delay timer, that could also affect start.
Do you have a voltmeter or battery charger to test the battery voltage? Can you jump the starter solenoid, from the battery cable terminal to the single switch terminal , to see if the starter will spin the engine?