Off the top of my head I would trace wiring looking for worn areas and check the thumb switches.

There are harnesses at the end of the left n rt hand controls under your tank that runs to your head light. If i remember right Theres a power loop that runs through both sides to the starter circuit. I may be wrong but im fairly certain the bike will do as described if either harness is seperated. I think its only two wires that effect it... maybe orange white n a grey? Anyway Pull those unions and sray some contact cleaner or something and push the little connectors into the harness as far as possible from behind after its back togeather to varify a positive contact. Always look for cracked or bare wire. And before u ride again tighten the bars by popping the caps on the riser clamps. Let me know what happens. Best of luck.