Well the seller doesn't sound all bad....just a novice it seems.
From what you describe it sounds like a neuro issues caused by overheating. I have seen it in snake before and it looked just as you described. I doubt the snake makes it much longer and honestly I would not try to feed it and cause any more stress to its fragile state.
Looking for a positive being it seems to be from overheating you don't have to worry as much about things left behind. I would clean everything with bleach and water as that is my main go to.