When I have enabled the encrypted partition of the NK Storage, inside Nitro-app menu a new entry will show up as “Gerät sperren” . What is the purpose of that entry ?
Just a quick step to throw out hidden and encrypted volumes ?
Or to burn a fuse to disable firmware updates ? 
“Gerät sperren” (=“lock device”) means to undo the PIN-entry and lock the device. Its basically the same as disconnecting and reconnecting the Nitrokey Storage.
Push , ok ! I read in a manual that a similar entry could be enabled to disable firmware updates. So I am glad that this is not the case!
Now I can sleep better 