Are these brand new aftermarket, or GM? EDIT: I just looked at the attachment, I see they're new aftermarket. When I got a new aftermarket FOB it didn't want to work until I pulled out the battery and swapped in another one. I checked the battery I removed, and voltage was fine, so maybe it was just not making contact for some reason. Once I put in the other battery it was fine. It could also have been I changed up the way I was trying to hold the paper clip, and push the buttons at the same time.
That new battery that wasn't working is going to get another chance, since I just got a new case for my original GM board. I'll finally have two key fobs. The original owners of my truck lost one in the first 6000 miles they owned it