What is the temperature in your brooder with a thermometer on the floor? Do they have a cooler area in the brooder to go to if overheated? Was she a feedstore chick or from a hatchery? Too much heat can constipate, and shipped chicks may get constipated as well. I would take a QTip and moisten it with vaseline or olive/vegetable oil and lubricate the vent opening. Get it drinking water by dipping it’s beak for a second a few times to drink. Then offer some chilled coconut oil cut into small pieces and let it eat some. If you don't have that give a ml of olive oil a drop at a time letting it swallow. Molasses (a few drops orally) would also be helpful to get it pooping.
The temperature is 85 degrees. They do have an area to cool off. I got that one from a local person that was selling them that a friend recommended. I tried giving her water and the oil. She didn't want any part of it. I have seen her eat and drink. I also put Vaseline on her vent. I will try again tomorrow. Thank you.