IS IT THE ANTI-THEFT SYSTEM OR SOMETHING ELSE

What is your question?

I have a 2009 malibu just brought it yesterday from a guy and spent a lot of money. Anyways I'm having troubles starting the car. My boyfriend asked to make sure the car started before we entered our home and upon entry I noticed the theft system icon was on (a car & lock symbol). I tried to start the car and it wouldn't start the lights on the inside and outside also flickered a few times as if an alarm was going off. I figured that this has to have something to do with the theft because the lights flickering. My boyfriend thinks it's the battery but the battery icon wasn't on only the theft icon. I googled a few answers to this problem and even watched videos on YouTube. After reading and watching videos I get back into the car to try it again and waited a few minutes with the key on the on switch and the radio lit up and flickered on and off eventually after sitting with the key on the on switch it seemed like the car battery died because nothing comes on at all.... What's going on?!? PLEASE HELP !!!