There could be infection spreading under the bark. Sooty Canker is one possibilty, black powdery fingus spreading under the bark. Have an arborist look at it. May be able to remove infect branches, tr ... read more
If it's solid red it might be indicating a tripped GFCI, if it's flashing it might be defective. When I say might it's because not all GFCI-s have the same type of light or color. Some are lit when o ... read more