Once you get it open, you may discover the cable needs to be tightened. If it has become severed :( I have an idea to share that I used on my old Pontiac Tempest:
Take a guitar string, it has a metal ball end. (The D-String is perfect size) and insert the ball end into the release mechanism, center.
Fish the other end of the guitar string thru the grill, and tie a loop so it doesn't get sucked into the engine. Pull on the guitar string to open your hood, and forget about the latch inside the car.
Hope it works out for you.
2006 Pontiac G6, 2.4L Ecotec
1993 SSEi "Bonnesaurus" sold regretfully 10-27-10