Burning finger after hand surgery indicates that the nerves to the fingers are regenerating and neurotransmitters are trying to get through.
In my lectures, I always told my students to think of a copper wire with a current going through it. If the copper wire is not pure, the electrical current will hit resistance. A resistor selectively resists current. When a transistor resists current, it heats up. That is why electrical devices heat up. Our nerve fibers are less selective. Neurotransmission is blocked when the synopses do not connect. When neurotransmission continues but hits a gap, the neurotransmitters are blocked and they heat up. Twisted nerves also heat up when neurotransmission is blocked. The same effect is produced when one is hit by lightning.