No power from battery
 

Hello!

I've had problems with my minicooper 2012 clubman since buying it, most of them having to do with a constant battery drain, bad grounding wire, etc.
Because of the battery drain, I unhook red terminal of the battery every day, and I believe this has caused a new problem with the antitheft device in the car that triggers everytime power is lost, because now there is no power with the battery connected.
When I connect the black terminal to the engine, though there is power and the car does turn on, the anti-theft device does not trigger the sound of a relay firing(?).
I was wondering if anyone had any info on what this is or how I can fix it.

Thank you for reading and for any help.