If you are just looking to help out, and not police, your friend with the new addition, then you can tell them what you know about BP husbandry and just exchange rat snake for BP. Temps should be the same, preferably provided by a heating pad under the tank controlled by a thermostat. They typically need less moisture than a ball would and they like to have a hide, just like a ball. Any substrate that you can use for a ball can be used with rat snakes.

What did they try to feed it and was the prey item sized properly? Did they try F/T or live? I don't know anything about the ecology of the snake in question but it is possible that they could be attempting to feed it the wrong prey items (i.e. mice to a lizard eater, lizards to rodent eater, etc.). How long have they had it? It may take a while for the animal to feel safe in its new surroundings and feel comfortable eating but after that it shouldn't be an issue. Did they try to feed it right after getting it?