Copying this from the other thread you made just in case:
Please bring your snake back to the store and insist that it needs to see a vet immediately. They will most likely require you to relinquish the animal back to them. Which means refunding you.
This animal is sick. that is it's intestine. It has to be seen by a vet before the tissue begins to die off.
Because of the possibility of parasites or bacterial infection that causes this, I would also consider returning the products you bought as well. Unless you would rather disinfect it all with something like a 5-10% bleach solution.
As a side note, a ball python will very rarely eat the next day after taking it home. Typically they will not eat for up to 14 days when moving to a new home.
I also don't understand why you are using a plastic bag to hold this small baby. The bag would be much scarier than your hand with a glove on.