Thanks for the quick response.
I tried both with all 3 bin files than (after that failed) only with the one that corresponds with my Kindle (update_duokan_0b006).
I copied all 3 DK folders.
I didn't press q, because I didn't even have the possibility to choose from the OSs, as the update failed, and the device just simply restarted (in fact I tried to press q during restart anyway, with no result of course

).