Juts check if the gear levers end is getting jammed against the side stand.
Does it make any noise while running? Do 1st and 2nd actually work? Might be something bent inside like a shift fork.
Agreeing with above, your missing kickstand is probably causing some weird issues on the electrical side which in turn is going to cause issues mechanically. This bike is very sensitive to sensors unfortunately, and I can only imagine when they're flat out no even there.
If it isn't running, not being able to shift through the gears is no surprise. You might be able to fiddle with it on a rear stand by rotating the rear tire and seeing whether it'll go up from second.
Might try rocking it back and forth while shifting.
Sequential dog face gear boxes need to be moving to shift or it is very likely the dogs won't mesh so you won't get the next gear.