Pushing start button does nothing

[otho96]

Hello i am not sure if this has been asked answered, i have searched these forums and have not found the exact same issue i am having.
I have a 2009 1700 classic. I went riding the other day and everything was great. I stopped did some shopping ate lunch etc.After my 5th or 6th stop my bike would not start back up. I turn the key bike cycles, dash lights on, radio plays but when i push the start button nothing happens. I tried jumping the bike still nothing. after bout a hour slamming bike in and out of gear mashing the start button it just started. I left the store and bike kinda ran rough, spiting and back firing. The bike died, i was able to push button and start it back up. When i decelerated the bike died again. this time was not able to start so i let clutch out and fired up to just die again. At this point she wont do nothing when pushing the start button. Push starting it will act like it will fire but does not, however does activate the head light once it tries.
things i noticed when pushing start button for over a hour, the FI light would come on and off, and 3 times now i have seen err 21 on display, this error code does not show up all the time and when it does it is 45 mins to a hour after continuing pushing start button shifting gears clutch and stand back and forth. I looked up the code from what i see says crankshaft sensor, on other vulcans nothing stating a 09 tho.
Battery is good and charged, all fuses have been checked. Any help would be greath