Car Alarms: how to turn off 1998 Forester after market alarm, brain box, chirps

Question
My 1998 Forester has the after market alarm system installed by the dealer when purchased new. The cars was serviced recently that required disconnection of Battery. The alarm is always on now, I do not know to to turn it off, please help.

I have tried the following as suggested by caralarmman:
- key in ignition and turn on,
- hold in the the alarm switch on the underside of dashboard,
- after about 10 seconds, the alarm chirps and unlock and lock the door, the red LED remains off
- the alarm is still on.

Please advise,

Thanks

Answer
Then it's time to pull the brain box from under the dash,
and reset the power. If that does not work, you may have
a short or a damaged alarm and would need to be repaired
or replaced. But without being there to evaluate it,
hard to tell.

Not uncommon for a fue inline to be blown when the
battery is re connected. I'd inspect the inline
fuses to make sure they are good, but really,
if it's functioning as you say, there may be
a fault on the circuit board.

Have this looked at by a pro. In the mean time
pull the harnesses off the brain box.

A.