Rattles, then shuts off on its own?

(I meant to write 90,800) Hi! So, I just recently bought the car listed above LT Hybrid and drove it home today, everything was fine. However, when I got home, I was adjusting some things (Bluetooth, audio settings, etc, ) and the car rattled very aggressively and shut off. For a brief moment a “service battery charger” appeared but went away. I looked at the touch screen and the battery is completely drained, and the check engine light is on. So essentially, I turn it on, it rattles aggressively, the engine shows a light moving to the empty battery on the touch screen, and then the car shuts off on its own, doesn’t matter whether I'm in drive or reverse, it shuts down completely. Luckily, I have a warranty and plan to fix it, just curious as to what’s wrong with it.