EWS is german acronym for the security encoded key and transponder.
Do you have a factory alarm on it? That could be the culprit.
If you don't have a factory alarm, people who have reported this problem before ended finding that the transponder ring around the hey hole needed to be replaced. Some dealers were clueless and spent much time looking for other things.. and in the end it came back to the ring around the key hole which "challenges" the key for the correct chip code to permit startup.
Let us know what you end up finding out...