I have had two of these same machines and both failed the same way.
I called 1-800-STARBUC and even though I did not have proof of purchase (first was a gift) they called my local store and the manager just gave me a new one.
It worked for a while and then poof. Same problem.
I know this is not a solution, but it just is not a very good machine.
I may tinker with the second broken one, but I don't feel very cheerful about my chances of fixing it.