The red arrows point to just some of the 24 components that were replaced in the amplifier of this IM3303. The homeowner reported that there were no signs of problems and the master station just failed of the sudden.
It takes a lot of heat for a long period of time to bake the two, 2-watt resistors into failure.
You can also see how the top of the capacitor have ruptured and push outward from the internal pressure of the failure.