Ive brought a 1999 A160 Avant-garde, The button key does not work and the doors have been opened with the key for ....... ????

My problem, ive brought a central locking kit for the car to replace the old pneumatic system the car has as standard. All's fitted in place and it works fine. My problem is the standard MB alarm immobiliser.
When i refitted the terminals to the battery the alarm went off... I have no button to turn it off. Ive never needed to before taking the terminals off the battery.
The engine will still start, everything works But, the alarm still goes off. So, Ive disconnected the siren, that was screaming and the indicators are flashing.
The indicators are still flashing for a while then they go off, come back on a few seconds later... Thats the bit i need to fathom.

Any idea's? There is no fuse in the fuse holder, so some ones obviously stopped this problem before hand. There must be a way. Or like my neighbor asked, Is there a manual key switch to switch the alarm of manually?

Ive spent all day on this and its proper fried my brain.