The Car Won't Start

Normally I would accept a battery problem and move on, but after connecting 3 different jumper cables (2 of those boxes and 1 actually to a car) at once, the electronics would work but the engine would just sputter like crazy and then die. Here is how it went down:

My BMW recently stopped starting. At first, the car would not respond electronically in any way. I had to use the key inside the remote to open the door. Then, I called BMW assist and they had a man come and try to jump it. He managed to get the lights and electronics to come on, but when I tried to start the engine, it sputtered like crazy and then just died. The speedometer read “Parking Break Fault” and something about lack of power. It sounded horrible when I tried to start it, it would rev up and and down, and then eventually just die. I just left the car there for now and will be calling BMW as soon as possible. Any ideas as to what exactly is wrong? I’m leaning heavily toward a battery issue but the speedo read parking break and insuffiecent power problems, the first one raises more concern. Has anyone had any incidents like this with 05’ 745s?