Push down on the atty and try to twist it off, if that doesn't work then take out the battery and turn on the hot water and wait until it gets as hot as it can get and run it over the top cap and where the atty attaches, then try to twist it off, it may take a few times to work. If that doesn't work put it in the freezer for 5-15 mins and try to untwist it. If that doesn't work you're going to need 2 special grip pliers or 2 vice grips and lots of masking tape or duck tape to protect your mod and atty from getting damaged and you would hold the mod with one while twisting with the other.