Will not start

If you could bypass the anti-theft system, a thief could do it too, so what would be the point of having the system? Actually, anti-theft systems are uncommonly effective at keeping owners out of their cars. This is not just a BMW thing, but it is why I drive older cars and let my newer ones sit at home. Much less chance I will be walking home.

When you said the driver's door does not open, I assume you meant the power lock does not work. That is likely tied in with the computer that has the anti-theft system built into it. One thing to consider is broken or frayed wires between the door hinges. There should be a switch in the lock mechanism to turn the alarm off. An inoperative power lock and an anti-theft system that can't be turned off are likely related to the same cause.

What are you hoping to do? I've never heard of a factory anti-theft system that could be bypassed. It is usually incorporated into multiple computers that talk back and forth to each other.

It sounds like the anti-theft system is not turning off. As I mentioned, they keep more owners out of their cars than they do car thieves. One thing to consider is broken wires between the door hinges. A defective switch in the door can do that too, but you can usually unlock the passenger door with the key to turn the alarm off. If a computer failure is suspect, that will almost always mean a trip to the dealer. BMW is one of the worst manufacturers when it comes to making their repair information available to anyone other than their dealers. They want to lock up all the repair business for themselves.

Please let us know what happens so it will help others

Best, Ken

If the heater core is leaking, you should have coolant condensing on the windshield when in "defrost" mode. It will also be leaking onto the ground from the drain tube behind and left of the right front tire. To create steam suggests coolant is dripping onto hot exhaust parts, and a better suspect for that is a leaking heater hose. This type of leak should be rather easy to locate by pressure-testing the system. Replacing a heater core is a big job on any car, and you want to be sure it is needed before tackling that.