As for the battery installation, I will have him look at that this evening but he has worked and built many cars so its not like he can't switch out a battery.

As for getting the old BCM back,,,,, remember, a dealership did the work and we never even saw what they took out. They just told us how much to pay and that was that. They didn't ask if we wanted them or to see them.

I'll get back to ya'll this evening with pictures.

Thank you so much for your help.

 

There are a lot of "experts" that don't know how to disconnect an HHR battery. The clamps are different and the sensor on the negative cable is not usual, it controls the alternator output.
Let this be a lesson; always ask for old parts, at least look at them. I bet the fine print on the work order you signed says something about it.