New chicken can't stand up, but is eating and drinking.

Hi guys, I got a new hen for my serama rooster, one of our family members also keeps bantams and agreed to let us buy one of their hens.

she seemed fine when we first saw her on the video call, and the first time I touched her a hot noon, which is also the day I bought her,she could stand.

I then played with my cousins, because we were set to go home at night , yes I'm a child.

so they kept her first in a bamboo chciken cage, then she was there for a few hours. It was very hot out so I'm thinking maybe she had a heat stroke? I didn't think she would be affected because the area at that time was a bit shaded.I know, I was wrong for this.

Thank you for your insights, in advance I'm a new chciken keeper so any help would be appreciated, thank you!!!