To be, or not to be. That is the question.
I have no idea regarding estar and ser, but I could not help myself.
Maybe this answer I found:
Although it is true that estar usually indicates a non-permanent, temporary condition whereas ser usually signals a permanent condition, you have to take into account that estar is normally used to express a condition resulting from a transformation, process or actual change, and ser is normally used when referring to an inherent characteristic, with no involvement of process, change or transformation; in other words, ser normally has the purpose of including the subject into a certain class.
This explains why there are some adjectives that express a permanent condition but can only be combined with estar: this is so because they express the result of a change or transformation; muerto is one of those adjectives, and another example is roto: el vaso está roto and not el vaso es roto.