1999 Mini immobiliser problem
I recently had trouble starting my Mini. The battery was replaced at Christmas, however, it is infrequently used and wouldn't start again the other week when I went to turn it over. While attempting to jumpstart it I have somehow managed to immobilise it so am now at the point where when I attempt to jump start it, all I get is a constant horn noise, and the engine refusing to start. I have replaced the batteries in both my fobs and tried to reset, but to no avail. No red light is coming on at all on the dashboard when the key is inserted. As said, the battery is new and the car's probably only done about 50 miles with it. Have tried disconnecting and reconnecting the battery, but to no avail.
Any advice would be greatly appreciated