I'm pretty sure that's a normal ball python I'm afraid
I haven't had any experience with burns first hand but because you don't know what conditions he was kept in I would see a vet strait away before Infection sets in. You might be doing everything right but he could have already picked something up from previous owners.
Not sure where your from but if I had bought that snake I would send picture and any details you have about the previous owner to the RSPCA to make sure they know what they have done/are doing is wrong.
Good Luck