Moo3264

It’s linked to a immobiliser and yeah sorry, it’s not actually starting

I have a Sinnis Terrain 125 and recently I’ve been having some problems with it. When the keys aren’t in, the light is still on the dash. It now doesn’t start up, I’ve got an alarm fitted so when I’m trying to start it the alarm is going off and the engine is ticking over like it is trying to start. I’ve took it to the garage and they replaced the battery but that’s not resolved anything but obviously with it being Christmas time the garage is now closed. Any ideas please? Many thanks