No power need to get to battery in trunk key cyliner broken what can I do. on 2002 BMW 325i

I have a 2002 bmw 325i and my battery is dead the key cylinder is broken so the key will not work I took out the back seat no way to the trunk from there anyone have any suggestions? I just need to get the car enough power so i can unlock the trunk.

Asked by for the 2002 BMW 325i