You can jump-start a BMW to revive a dead battery, but to do so, you'll need the power from another vehicle that is running, and a set of jump leads. Although BMW models store the battery in the rear of the vehicle, you can jump-start it from the front. You can find the red positive (+) connector under the hood and next to the engine. Once you start it, you'll have to let the battery recharge before turning it off again.
Pull the working vehicle up to the dead-battery BMW. Do not let the two cars touch, but make sure they are close enough for the cables to reach under each car's bonnet without becoming taught.
Open both bonnets and keep the jump-start vehicle on. Do not turn it off. In the BMW, remove the key from the ignition, turn off the radio, any heat or air-conditioning controls or interior lights that are in the "on" position and close the door. Doing so can eliminate pulling power from the other vehicle before the battery has gained enough power to start again.
Clamp the positive jump lead onto the BMW's positive terminal. Squeeze the handle to open the clamp and release it onto the knob. Do the same to the working vehicle, connecting only the positive part of the battery and the cable -- both are red.
Place one of the negative (black) clamps on the negative pole of the booster car. Ground the other end of the negative jump-lead connector to the BMW by clamping it onto a non-painted metal part of the car, like a bolt or metal piece in the front portion of the engine bay.
Open the driver's side door of the BMW to get in and close it quickly. Start the ignition. If the BMW does not come on at first, wait a few minutes before trying again. Once it is started, leave it running.
Disconnect the jump-leads and do not let the cables touch while doing so. Take the clamps off of the BMW and then the jumper-car. Drive the vehicle for about 30 minutes to recharge the battery.
If you have to constantly jump-start your BMW, this could signify an electrical problem or that you need a new battery. Take it to a mechanic.
Do not tamper with a battery that is corroded or with cables that have wires showing.