The starter system is fairly easy to troubleshoot.
Start at the battery + and using a test light or meter work your way back.
We know the 40 amp breaker is good since his lights and dash work.
Go through the 10 amp fuse, through the ignition switch, run/stop switch, start switch and to one side of your starter relay.
If you have 12 volts getting there, then check the clutch switch that should provide a ground to the other side of the starter relay coil.
With a good 12 volts on one side and a good ground on the other, that relay should energize, providing a massive 12 volts directly from the battery to the starter.
If it doesn't then replace the starter relay.
You could also test the starter, put your bike in neutral and leave the key off
, you don't need the bike on to test this.
Short out the two large cables across the starter relay, this will put 12 volts directly to the starter and it should turn the engine.
Of course it won't start because your bike is off, but it should still turn the engine. If it doesn't then you may have a bad starter.
Hope this diagram helps.