Problema Alarma BMW/ encendido

[Chema GB]

Hi everyone!

The other day I was finishing fixing some things in my 318IS and I connected the battery that I had removed to work.
Whenever I disconnect the battery, when I reconnect it, the alarm goes off and I can't figure out how to stop it, sometimes by locking or unlocking the doors and sometimes it just stops.

The question is that when I wanted to insert the key to start the engine there was a tab that did not allow me to insert the key.

After manoeuvring for a while I managed to get it in, but when I turned the ignition on, the dashboard wouldn't light up and it wouldn't let me turn the key any more to start the engine. It doesn't work with the battery disconnected either.
My question is: Does the alarm have some kind of immobiliser? I know that the original BMW alarm cuts the injection, but I don't know if it has a locking system for the cylinder, as the key has a light or infrared (I have disassembled it and it is a light attached to a battery without a motherboard).

The battery works correctly at 12V and on the other hand I have the driver's door lock broken and I don't use it, which is the one that triggers the alarm.

Thanks for your help.