julia it sounds like it is in lock out because your son has tried to put the wrong No in,
after 19 presses of the wrong No it goes into lock out, To reset it if you are compitant enough turn the electric off to the alarm panel.
and now remove the front cover on the control panel and disconnect the battery and wait a few seconds and reconnect the battery, if the alarm goes off when you disconect the battery dont worry when you connect the battery back up you can put your code No in should stop it,
now put the cover back on and press reset and all should be ok now switch the power back on good luck
baz26
February 2010