2 folks have said to turn it with the Allen wrench to unjam it, but
they didn't say to turn it *backward* to unjam it. Hopefully that will
free up whatever has it jammed. If it's humming, odds are the breaker
on the unit didn't pop, but it's worth checking anyway.

Indeed!

You usually "wiggle" it back and forth until it moves freely.

If it "jams" very soon again without obvious cause (you don't put another
spoon down it) you can get a flashlight and look inside for something that
should not be there. Use common sense and whatever is handy to remove it.

Another trick before replacment is to remove the outlet tube and see if
there is come kind of back up. Again, use common sense as to the best way
to remove "stuff."

As they age, they get "sloppy" inside and don't chop as well. The bigger
pieces tend to jam.

As things go, disposals are pretty cheap (if you don't get carried away) and
easy to replace. Find a model with the same dimensions and you can replace
it in a few minutes. You can leave the part what attaches to the sink.
You remove and attach the electric while the disposal is sitting down.
Then it's easier than changing, say, a worn out switch.