I just recently bought a 84 firebird and the guy I bought the car from didn't have the door key for the car, so I'm changing the door locks and trunk lock, anyway today I drilled out the trunk lock and tried to pop the trunk by sticking a screwdriver in the slot on the inside, I turned the slot but the trunk won't pop open, could the trunk latch be defective? is there a way to pop the trunk open from inside the car trunk on the inside latch other than turning the key rod slot? This car doesn't have any power trunk release everything is manually operated. And it looks like the trunk hasn't been opened for a very long time.

Inside at the rear trunk panel, is there a light bezel like the one in the picture? If so, then pop off the light housing (#3) and insert a small flat head screw driver into the slot (#1)and turn . If you dont have a light lens there at #3, then pull off the passengerside rear tire well housing panel. If the firebird has a aftermarket lock, then there will be the OEM lock cylinder housing with a black cable attached to it (#2) hanging around the area circled in blue (#2). Insert a flat head and turn. Should pop open trunk. This is how my 86 Camaro is set up. I dont know if this method applies to your 84 Firebird. Good luck.