You might try
- make sure the battery is 100% charged
- then crank the bike with the throttle wide open, no more than 10 seconds straight, let the starter motor cool between. This will help clear it out if loaded up.
- then try with throttle closed, hand off the grip.
- if still no go, try remove and clean the plugs. While the plugs are out, test for spark.
I had a problem like that earlier this year. Took the battery out and put it on a tender inside so it wouldn't freeze. When I put it back in the bike I hooked up my PC to the positive rather than the negative. Was cranking all day long with no chuff. So you may feel kinda :tard: right now but at least you didn't have to pay the shop to tell you you're a dolt. :sbmfacepalm: