Under Australian law
http://www.accc.gov.au/consumers/con...replace-refund
You are responsible for returning the product, unless the cost of doing so is significant. In this case, the business must organise and pay for the return or exchange.
You do not have to return products in the original packaging in order to get a refund.
e-reader-store.de/Booxstor should refund the full price of the reader and postage to and from their store, regardless of the packaging condition, if the reader is found to be defective.
The e-reader-store.de return condition is absolutely disgrace on the Germans.