Elise S1 immobiliser problems

[Nath V]

Having a few issues with my S1 Elise, go to start the car and the key fob won't disarm the alarm/immobiliser, try new batteries and then the manual override stick but still nothing.

Trace the problem to the 10A alarm/interior light fuse, change fuse, hazards flash, alarm beeps then fuse immediately blows again.

Would be grateful if anyone has some suggestions as to what it might be or things to check?