Fourtrak, F78, N reg, immobiliser fault


Hi Everyone,
Wondering if anyone can give me an idea on why my immobiliser will not cancel to allow me to start vehicle. I have just replaced the battery on the vehicle and used jump leads to boost start it, so maybe there is a sequence to reset the immobiliser - genuine Daihatsu immobiliser fitted (small black plastic fob with three electrical pegs). Or failing this is the immobiliser easy to bypass?