Here's what to do. Get some oil into the chick immediately. Coconut oil is easiest because you can slip solid bits into the beak without risking aspiration. But mineral oil or olive oil will do.
Coating the stem with oil should permit it to slide on out of the crop and make it's way through the intestines and get pooped out in a few hours.
After administering the first half teaspoon of oil, massage the crop for a few seconds very gently. give the chick a rest and in half an hour administer another half teaspoon of oil, massage for a few seconds and wait for the stem to show up in the poop.
During this, provide fresh water to the chick to drink. Chances are it will feel the need to try to wash this stem on down the digestive track.