Have activated Brinks system without contract! Need to deactivate!

["thomas" <thomast0001@xxxxxxxxxxxxxx>]

I bought a house recently with a Brinks system installed.  We do not
have a Brinks contract, so the system technically is "inactive" and out
of contract.  Just today the alarm keypads started beeping due to a
low-battery warning.  Not knowing what to do I pushed a couple of
buttons on the panel, and much to my surprise when I pressed the On
button the system went active (on)!

I immediately disabled the motion sensors (pressed the Motion Off
button) and called Brinks.  They explained how to power down the panel.
 I disconnected the backup battery first and then disconnected line
power.  Brinks assured me that after doing this, if I hooked the panel
up again it would be inactive.  Well, I did power up the panel and it
immediately went into the active (on) state again!  I tested that it
was really on by openning an entry door.  The key pad started beeping,
indicating that the disarm code needed to be entered.  I immediately
RAN to the panel and disconnected power again -- I didn't feel like
listenning to the siren go off.

Soooo, what do I do?  I don't have the master code from the previous
owners.  Anyone know how to turn this system off again without the
master code?  Per some suggestions from other posts I have disconnected
the panel phone line.

The panel is a BHS-1200 (Sentrol, Inc. P/N 60821564 A).  The key pads
are Scantronic DCU-602 series, P/N 101-000121.

Since I'm not too concerned about monitoring (the alarm horn should be
good enough for now), anyone have a good suggestion for a replacement
panel?  This is a wired system, and all wires are pretty clearly
marked.  I just need to know what to buy.  As long as the wiring is
compatible I know I can replace this all myself.

So, any suggestions?