Opening ANY electronic device is not a good idea. You allow dirt, dust particles to get inside and potentially cause other issues which probably will not be fixable. As well as the possibility of dropping something on the open portion and totally trashing the device.
People just leave the device alone till a fix is sent our then deal with it then. If you break the case or screw up the inside while opening it, who are you going to blame then??
Zune is AWESOME!!...since Nov 2006 Black30GB and Pink30GB (my wifes'!!!)