How do they treat blisters and burns?

Symptomatically: Cool compresses and caring for the resultant wound/open skin is about all one can do.

Keep it clean: My recommendation is to always remove blisters. This will allow any topical medication to reach the actual wound. Also, the presence of a blister denotes a partial thickness injury. If the blister becomes infected, this can rapidly progress to a full-thickness wound. Removing the blister eliminates this possibility, allows direct inspection of the wound.