Accenta 8 Mini Alarm System?

We have the above alarm system which was working fine, last week when we entered the house my dad entered the wrong code several times until finally getting the right code and the alarm turned off. I then press the reset button because the alarm did not go to work next time. So when i pressed the reset button as i have done before, the tamper light came on and has stayed on ever since. For some reason the alarm has frozen and we can not do anything to get the tamper light off. Can you please help.