You can replace discharged remote battery in your Volkswagen Passat B6 key fob yourself. Start with removing plastic key from the remote. Now press on the chrome part of the remote. Do it on the side without key release button. Now you can pry plastic cover and open your cars remote. Inside you’ll find single battery, that you need to pry to remove. Install new CR2032 battery inside the remote and put the remote back together. Your cars remote should work instantly, no need for reprogramming it.