Holding the arm and disarm simultaneously will toggle from "silent arm" to "audible arm".
These fools at the install place are now trying to tell me that the alarm may have been in the factory head unit they just replaced.
After fooling around with several combinations of holding the both buttons I was able to re-enable my alarm. I'll try to figure out exactly what I had to do to get each result and post it for the hell of it.
Just to let you know, there's not much features in the factory alarm. It basically lock and unlock your door with the horn honking or lights flashing. That's why I figure if you say the alarm is disable and acting like keyless entry they must have turn of the horn accidently.