w202 C180 immobiliser
 

After reconnecting the battery after doing some work on my C180 the alarm / immobiliser has re-activated itself, it didn't work when I first bought the car, and i can't deactivate it. The alarm / immobiliser appears to be a dealership / after market system as the light to indicate the alarm / immobiliser is working is in the dash rather than on the central locking switch as detailed in the owners manual. Can anyone give me any ideas as to how to sort fix this problem?