Rescue situation, newer keeper

[Bogertophis]

So, regarding his back it’s really scaly with a few raised areas. The first thing I asked was if there was a heat lamp, because I was immediately thinking maybe a burn. But they didn’t have a heat lamp...

Just keep in mind that when people give up their unhealthy pets to others, they don't always tell the truth about how the animal "got that way". I've heard a few tall tales myself. I'd personally still consider this might be a burn. I'm not saying it is, I'm just saying it still could be.