Second time In two months that battery died overnight. Jumped battery and left it with nearest dealer, same as before. Same result - battery charged and codes cleared with no clue what is draining the battery. Took it to original dealer across town. They said there “might” be a software fix. Software for brake system module was updated. So far, so good after two days. Dealer said that a few others have the same issue. They pressured GM for a solution. GM suggested the software fix. Stay tuned.