The key is to not plug it back in to sync with the software. You can plug it in to charge from your computer, just dont let the software (Zune) auto start. You can turn it off in the options of the software before plugging in your Zune. As a side note that may be helpful, if you dont have a screwdriver small enough, and you have children that play with TechDecs, ask them for one of their screwdrivers for the techdecs, they are the perfect size. Also, be very careful about where you put whatever it is you use to remove the clip around the charging jack, be sure to use something like an exacto knife and lift at the points where the clip is the thickest, which should be the right and left sides, not the skinny parts that run the length of the interface. The clip will break at it's skinny spot. But just for the sake of clarity:
DO NOT PLUG BACK IN TO YOUR COMPUTER TO SYCN AFTER COMPLETING THE BATTERY FIX!