The answer
Buzzing indicates electrical arcing (current jumping across loose screws, backstabbed connections, or worn contacts; produces >1,000°F heat). Warmth indicates continuous electrical resistance or overloading. (Dimmers dissipate slight heat normally, but should never be hot). Action: Shut breaker off immediately and replace device.
Sources
This answer is drawn from the standards and guidance below. It is general information about how these systems work — not a diagnosis of your property.