A-833 Stuck in gear

Either the lockouts are confused or the slide ring that the shift fork moves to change gears went off the end of the travel too far and is stuck there because of it.
Pulling the side cover is pretty much mandatory at this point if nothing will move.
Pull the cover and look at the slide ring for the front fork and I'll bet you find it's stuck.
If it isn't then the problem is in the cover and it's related shift fork and lockout (detent) parts.

Or like Del said, you might have missed it with the fork.