Car problems, car is losing power and dieing?

So my car died at a gas station and I got it jumped . 5 minutes after driving the cd player started blinking off and on and this weird light came on with a ! and a circle around it. then i lost power and i couldnt go past 40 mph then as soon as i pulled on the side of the road it died again i got someone to jump it and i made it 5 more minutes then it did that stuff again and then the whole trunk filled with smoke and it died the battery is in the trunk. I drive a 1993 bmw 325i