Find a better one.
Basically, the circuit will be broken somewhere around the starter motor, ignition, fuel pump or similar essential operating system. It will also be earthed somewhere.
It will probably have a connection to a switched live as well and will likely have been wired into the Wiring Loom, so you'll probably need to open that up. I'm guessing there's a connection to a permanent live too.
When you switch the Immob off, it makes the connections. When you switch it on, it breaks those connections and thus immobilises the bike.
Identify the Immobiliser unit and track all wires, figure out what they're interrupting and re-connect.
If you can get the Workshop Service Manual for your model of bike, that should at least help identify the components by appearance, plus it will include a wiring diagram.
Basically, anything not shown in the manual (assuming your electrical system is otherwise unmodded) is likely to be part of the Immob system.
This is why it's usually best left to a professional.
Check also that it's definitely a broken immobiliser and not some other circuit system that's damaged.