Not sure what he's expecting to change with the key in the on position, that will charge the key battery but that is not used for ews.
EWS stands for "D rive A way P rotection"
I've always wondered what the letters meant. It makes more sense in German:
Electronische Wegfahrsperre
http://www.unofficialbmw.com/images/BMW_EWS.pdf
That article could be of major help in flushing out your bug.