Hyundai Repair: 1997 Hyundai Coupe Central locking, toad ai606, door latch

Question
The central locking on my coupe/Tiburon is not working.

I have an aftermarket alarm system (TOAD AI606. the alarm system locks the doors when activated, much in the same way as the remote fob.

When I Alarm the car the doors dont lock, instead I hear a clicking sound, Ive looked into the clicking sound and its coming from a black box, I asume this is a relay of sorts. I have replaced this thinking that is was the issue, but my central locking is still not working.
If I use the key in the door lock it still doesnt work (tried both doors)

What else could be causeing this not to work.

Answer
If you're physically unable to lock the door with the key, then you have a mechanical issue with the door latch or door lock actuator.

If you simply cannot get the power locks to operate, then you could have a blown fuse or an open circuit in one of the door lock actuators.