Scantronic 9450 tamper alarm keeps sounding?

Hello,

Wonder if you can help me? We have a Scantronic 9450 that starting this week kept sounding the internal alarm with the tamper button highlighted (this gets a little wearing after the fourth time in one night) My husband has removed the battery had it tested (flat as a pancake) and replaced it with a new one. All was well for the first 15 hours then it was started again every few hours going into tamper mode!! Someone has suggested that I need to reset the system using the engineer code? - I think I know what this is but have no idea as how to reset the system.

Any help would be really appreciated.

Many Thanks