Motorcycle Questions? Ask a Mechanic.
Your starter button is probably shorted internally or in the wiring leaving it.
You can remove the fairing and either remove the starter button wire from the right side control plug or just clip it to see if the problem is solved. If it is you'll know the problem is the switch. It isn't common but it does happen.
The red/black wire in the right control housing is the wire that the start button energizes so that is the one you want to check. It should show no power with the bike on and should show power when the start button is pressed. I can send you the wiring diagram or help walk you through the troubleshooting if need be.
I hope this helps. Please let me know if I can be of further assistance. Thanks, P.J.