Alarm keeps going off after Headunit install

Hi everyone

I recently replaced the head unit (radio) in my non JBL Headunit and ever since my immobiliser alarm keeps going off. Does anyone know why this may be happening/ how to resolve this? I’m currently waiting for my resistor to arrive so I can bridge the cables behind the climate control screen to get that working, don’t know if that has anything to do with it.
Would appreciate any help