Almost sounds like a switch for the lights. I can't believe all bulbs would burn out at once, unless there was a hell of a spike. As for the code, what was it, that helps a lot.
You have two brake switches, one for stop lamps, and one for TCC control and cruise. Possibly the bracket that holds the two came loose.
I know they have had problems with switches going out of adjustment, why, I don't know.
Let us know what the tech said, and next time, ask Onstar for the code number, that helps me greatly.