Oh dear. Your Dad has probably heard that story for years when he was growing up. It's still going around. But a parent bird will not reject a baby that's been handled by humans. Most birds don't have a great sense of smell. Mammals do but even they will take back their baby if it's returned within a day or two.
I see two options: put the young bird in a small box or berry basket type thing and tack it up in a tree or bush near where the baby was found. It will call, the parents will find it and continue to feed it. Or find a licensed wildlife rehabber in your area. They have the permit to care for the bird as well as knowing what type of food to feed it and how. Birds have a hole (glottis) on their tongue where they breathe. It's so easy to accidentally get food or liquid into that hole and it will go down to the lungs. Then baby gets pneumonia and will not survive. That's why a rehabber is the next best choice if you can't get it back to the parents.
As you see already, the baby is shutting down and not responding well to human care. It wants its parents. Please try my suggestions. A rehabber can join the baby with others of its kind and that will help a lot in terms of care.
Hello Kyra4452, Ireneo is giving you excellent advice. She is right.
A parent bird will not reject a baby that has been handled by humans.
When you choose a small box to put the young bird in, just make sure
the sides are high enough so that the little bird will not fall out of the
box accidentally. As Ireneo suggested, tack the little box with the baby
magpie inside it, up in a tree or a bush near where the baby was found.
Do not put the little box with the baby magpie on the ground. There are
too many dangers on the ground. Another animal could find it and do
it harm. Personally, I would try and choose a tree to tack up little box
containing the little magpie , but it must be near where the baby magpie was found. The baby magpie will call out and the parents will find it and continue to feed it. and look after it. The baby magpie needs to be back with its parents feeding it. I know you want what is best for the baby magpie . This is the best option. If you do what Ireneo suggests, there is an
excellent chance you can reunite this little baby magpie with its parents.
I wish you and the baby magpie my best. Eve