As you saw, Mama had no problems getting that chick to the coop floor. That has been my experience with nests even higher. I know you read a lot about how you have to help them down from elevated nests but I don't and I've never had a chick hurt getting themselves down.
If the hen is sitting on that egg I'd leave her alone for another two or three days. Since she abandoned it there is a poor likelihood that it will hatch but give it every opportunity. If you mess with her you might cause her to abandon it.
Those holes on your cage look big enough that the chick could get through and away from Mama's protection. If you are going to lock the hen up make sure the chick can't get out. If it is out with the other hens and Mama can't protect it then the chick is in danger. You might try wrapping the sides in hardware cloth or plastic netting to keep the chick in.
If the hen is sitting on that egg I'd leave her alone for another two or three days. Since she abandoned it there is a poor likelihood that it will hatch but give it every opportunity. If you mess with her you might cause her to abandon it.
Those holes on your cage look big enough that the chick could get through and away from Mama's protection. If you are going to lock the hen up make sure the chick can't get out. If it is out with the other hens and Mama can't protect it then the chick is in danger. You might try wrapping the sides in hardware cloth or plastic netting to keep the chick in.
