Speedfight WRC 50 no Spark/Start?

My daughters WRC 50 has been battling to start on and off for a few months now. As of Yesterday it won't start. I bought a multimeter to go through the manual steps of checking the resistance of HT Coil primary/secondary, spark plug and cap - all ok. Not sure on the Pulse coil if I'm getting the correct reading and on the source coil.

My real question is when/how do you know if it's the CDI unit or the immobilizer? The LED for the immobilizer has never been active since we bought it. So how would I know if it is actualy deactivating? I did check the LED with the meter and it looks fine so should light up???

ANY POINTERS would be appreciated