I picked up a Ducky One Mini at a flea market yesterday, and after cleaning it extensively it seems to be working pretty well for the most part. I'm using it for writing and coding, so not having dedicated arrow keys will take some getting used to, but other than that it seems neat enough for the price I paid.
However, the alternative graphic button (on the right side of the space bar) is completely unresponsive. Pressing it just makes no difference at all. I used a tool that maps keyboard presses in Linux (xev), and it showed nothing when Alt Gr was pressed (just like the Fn button), so it seems no signal is being sent from the keyboard to the computer.
It could be that this is due to some setting made by the previous owner, or maybe there's something else going on. Maybe I need to update the firmware. Maybe it's broken. I have no idea.
The back-light behind some of the numerical keys is also disabled or broken, but it doesn't bother me much as I'm not a big fan of back-light anyway.
But if anyone has any suggestions what to try for the alternative graphic key it would be much appreciated! For now I have re-routed right super (Windows button) to be read as Alt Gr, but it's not very convenient when writing Latex and using a lot of curly brackets. :)
Before opening up or resoldering any switches, I'd short the two pins with something (tweasers or similar) to confirm or rule out the switch itself as the cause.