If everything powers up and it goes click as the solenoid engages and does not turn the motor over, it's low voltage, bad starter or a fuse is gone. If the starter spins but the motor doesn't turn over it's the sprag clutch. And If the exhaust valve goes bad, no start typically (but should see a code). I doubt the starter failing pops up a code. It certainly didn't do it on the earlier bikes. You can check the starters by using a DVM and checking the resistance to ground (starter hot lug, battery ground). Should be only a few ohms. If the resistant is high or infinite the starters checked out.