You have to remove the box from the car, don't disassemble it in the car.

There is a fifth attachment underneat the box, near the crash sensor for the airbags. Look in front of where the ashtray used to be.

The box is rather well attached to the firewall by all the sealant (caulk) the factory used. Pry all around it to work it away from the firewall. It takes some time, and it takes some force.

Good luck,

- JimY