This may sound weird. But it is possible to force feed it. I learned this technique years ago whenbi raised birds and the past week it's proven successful with chickens.
You'll need a syringe. It has to have an extension on the end. It cannot be one designed to receive a needle. I use one I got from
Walmart Pharmacy that is meant to deliver medicine to babies.
Next you'll need a tube small enough to fit the end of the syringe. I cut up a... Not sure of the name, but its one of those hoses that hospitals use to deliver oxygen to patients.
Next mix some form of soft food. The people here could tell you what to use better than I can.
Make sure the end of the tube not connected to the syringe, the part that will go down the chickens throat, isnt going to cut or scratch. I used a hot knife to sort of round mine off.
Have someone hold the chickrn and wrap your hand ariund the head. It doesn't have to be a tight grip, just enough to stop it from shaking/moving its head from side to side so it doesn't break its neck.
If you can, use the same hand holding the chicken to gets its mouth open. I generally pinchnthe bottom beak with the same hand holding the head and they open their mouths themselves.
With the syringe in the other hand, place the hose (it should be connected to the tip of the syringe, and what ever your going to feed it needs to be pushed to the end of the tube, so you aren't injecting a tube full of air.) Anyway, place the tube in its mouth, on top of the tongue, and slide it gentlydown its throat.
This is the tricky part. You need to feel the tube going down its throat. Placing your fingers on each side of the throat will allow you to feel it as it slides down. You need to make sure it goes into the craw. The craw is located directly under the knot where the neck connects to the body. It seems way farther down than it should be to me. It's weird after dealing with parakeets and the like.
Once you're sure the tube is in the craw inject the food slowly. If there are any chunks stopping Smith flow through the tube, don't force it. Remove it, unstop it, and start over.
Last, bit not least, don't overfill the craw. That's bad.
Not sure if this is something normally done with chickens bit its a lot easier than using an eyedropper. For me and the chicken.