Hi guys,
I have a 06 SS with 120k miles on it. I recently let the car sit for about two weeks, and I went to drive it yesterday and it is dead. The power locks seemed really weak at first and I couldn't get the back hatch to open using the key fob. I popped the hood and then hooked up the battery to my jeep to jump it. I tried to charge it for about an hour, maybe a little more, and the lights would start to get brighter, along with the radio and display turning on. However it would not start, and I would here a clicking noise from the starter it sounded like. Then all of a sudden, it was dead in the water. No click from the starter, no lights, and I could barely get the key out of the ignition. Could it be that my battery is just as dead as a door nail, or could it be something worse like an alternator? I am going to go get a new battery after work today hopefully, if I can get the old one out.
Thanks!

 

I would bet its the battery.. Had almost the same problem with my bonneville.. Couldnt believe it when everyone here told me the battery was shot.. Turned out to be..

 

yea, I also have an 06 SS that sits inside the garage for weeks and/or months at a time.
A while back it sat for about 3 months untouched, went to move it and dead as a hammer. I tried to charge the battery but it wouldn't charge. Put a new one in and it fired right up. Since ive been adamant to start it and let it run a few minute every once in a while or just hook a battery tender up if I know its goin to be in hibernation for weeks.
I got no idea what kills the battery from just sitting. I was suspecting the onstar system may somehow be trying to communicate or something I have nothing to prove that theory however.
Getting the battery out/in is a little pain in the sack. You about need a helper to assist. Once you get that brace off that goes over the top I found it easier to unbolt that black box on the fender well, have someone slide up and hold it out of the way best you can. You can leave the wires connected. Then you can fish that battery in/out.
also for note in my instance when I did have this issue. upon startup I was getting a "service charging system message" on the cluster. However everything was fine. The battery showed 13v and when running the alternator was putting out 13.9 v. Turned out that there was an update for the bcm to be flashed that I had to have done at the chevy dealer. Again no idea if the battery doing dead as crap for months caused the bcm to loose prior memory but again its been 2 years ago and hasn't happened again. I hate electrical stuff gremlins lol

 

Sounds like a battery to me. When they get old they still need to run all the systems when the car sits and it will make them go away.