I've never heard of a key being stuck in the ignition due to a dead battery. I thought the key insertion/removal was a purely mechanical process. Is your car Tiptronic, and if so, are you sure it's in Park? Is your steering wheel straight? Is the steering wheel stuck against the right or left side, locking it against the ignition lock? Try turning the steering wheel slightly to the left, with one hand while pulling on the key with your other hand. If that doesn't work, try the opposite.