how to open hood if the release latch under hood will not open it
your latch cable probably broke. you are probably better off going to a body shop or repair shop. I am not familiar with your cars latch set-up but sometimes if you jack car up on jack stands you might be able to see the latch from under the car. you would then need to get to the latch from their using what ever would reach it to try to get it to open. if you can see the wire in the cable right by the latch try pulling on it with long bent tip pliers. sometimes your lucky and can get to the latch through the front grill. but if you dont have extensive choices of tools to choose from to help you it will be really hard to get too.
Have someone try pushing down on the hood while pulling the release handle
I had that exact problem on my Corolla one time. The cause was just that the latch mechanism hadn’t been lubed and it just got stuck. First I rigged the passenger compartment latch release so it would stay in the release position. Next I crawled underneath the car, with a flashlight looking up into the latch area. I found I could see better in the twi-light hours, less ambient light. I could see the cable going through that area. (Helpful if a helper were available to manipulate the mechanism in the passenger compartment at the same time, but not necessary.) I used a pair of long forceps (like surgeons use to clamp arteries) to grab that cable and manipulate it while pushing up on the hood. Eventually it popped the latch open.
I learned my lesson and now I lube the latch mechanism w/every oil and filter change. Can’t speak to whether this method will work on your Cobalt of course. It did the trick on the Corolla. Best of luck.