...Well I don't know what I did differently, but it worked this time...? -.-You just need to download the firmware and extract the zip to a folder on the SD card. Search Google for darth (you'll have to combine with another word to find it, unless you want to get Darth Vader results. )
Once the folder is sitting on your SD card, you can install it with daybreak (included with Atmosphere in the homebrew folder).
Can't help you any further, as I never even used nxdumptool myself. The picklock thing does fully support v17.0.0, as it does its job and dump the keys properly. The rest is up to you and nxdumptool. Maybe someone who uses that homebrew can help you, hopefully. Good luck!
Whatever, anyways, managed to dump an eshop game's files...gonna go ahead and make a new thread and hope I can get help on modding this game, of course the files have to be difficult. lol