[chairman]

Almost looks like a minor burn. Do you have an undertank heater? Is it controlled by a thermostat (not a rheostat)? Can you measure the surface temperature of the hot spot with a infrared/non contact thermometer/temp gun?

Not trying to undermine your vet but electrolyte soaks are mostly useless with snakes. They are only beneficial if your snake happens to drink while soaking; the snake's skin doesn't absorb nutrients. (Electrolyte soaks are useful for tortoises because tortoises absorb nutrients through their cloacas.)

The only worthwhile soak substances I know of are water for shedding issues and chlorhexidine/iodine for topical infections.