I've got a red xyloband from the Köln concert last week and I haven't noticed it glowing until now. I tried opening it up but I couldn't make much sense of the circuitry. I suggest, some one who knows something about electronics have a look and he/she would have better luck figuring out how to get it to work.
Also, if any one has a radio frequency generator could play around and find out what gets these cool things flashing.