Auto Parts: 2002 VW Jetta 1.8T, jetta 1, vw jetta

Question
I recently bought a replacement shell for my beat up key remote. I transferred the inner components and even managed to get the blade to flip out on its own (lill tricky). All worked fine for about 3 to 4 and then the immobilizer kicked and all went south from there. the local dealer wants $100 for programming and are their kind enough to throw in the battery for free(jerks), my question is did i miss something in the old case or can these keys so easily deprogram by removing the battery I would really appreciate some advice.  

Answer
    I don't really know much about VW's remote security system.  Most computerized devices can have the battery replaced without screwing up their built-in programming.  Car stereos are an exception, for a good reason.  The same reason may apply to the VW key fob.  But, if you are saying that the engine started and then quit after 3 or 4 minutes, that's about right for a bad fob.  These things are little Radio Frequency transmitters, and there is a little receiver built into the car very near the ignition switch.  If it can't talk to the key, then it shuts off the car.  So, it's possible that you did something to the key assembly that damaged or disabled the transmitter.  I would be tempted to try to find a good automotive locksmith.  He could get you going again, I'm certain of that; they have all of the fancy gear for testing and reprogramming these remotes and RF keys.  However, my experience with these guys is that $100 is about what they are going to charge you, so you might just want to bite the bullet and let the dealer fix it for you.  However, I'd make them tell you what you did wrong so that you will at least learn something out of the whole ordeal.