This happened to me on my 07 H2. I would have to jump sart my rig about once a week. I took it to the dealership and they told me they would look at it the next day. they gave me a loaner H2 and off I went to work. That evening I called and they said there was nothing wrong with my truck adn i coud get it in the morning.
The next morning, I drive down to get it and meet with the service manager. He grabs my keys and walks back up to me and tells me the truck wont start.
So he decided to replace the factory battery and all is well with the world. He mentioned there was a batch of factory batteries that seemed to have problems and this is what he based the replacement on. Haven't had the problem again and its been about 1.5 years on the new battery.
He stated they checked the battery and charging system and all seemed to check out, so he was confused but glad to see i was happy.
Have em swap out the battery, I bet that'll fix yours too.