The battery is dead on my pontiac pursuit (same as Cobalt). The ignition won't let me have the key back, and because the battery is dead the button to pop the trunk doesn't work. I have a battery charger. Can I attach it to the battery terminal under the hood to get the battery charged?
Absolutely. Attach to the positive/negative posts there and it will charge your battery. Really, that's what they are there for (and so you can give someone else a jump if you needed to.) You'll find once you attach the charger, you'll be able to pop the trunk ... so if you want to change that over to the battery at that point, so be it.