WTF...The saga continues

[H3PAC]

I think the most likely culprit is your battery. I had the exact same problem you had and it took multiple tests for the battery to fail. It's not unusual for a defective battery to behave that way. Ask them to just replace the it and I'll bet you your problem won't repeat itself. And by the way, tell your dealer to give you a reasonable loaner. What kind of Hummer owner would want to be seen in a minivan? Do they think you look like a soccer mom or something?