OnlyKey works fine on my early 2009 iMac. However, on my mid 2015 MacBook it won’t load. When I first plugged it in, the keyboard assistant was showing. I clicked the red close button on the window. The OnlyKey flashed some colors as usual but then, after a few seconds, the light went off. Nothing happening, no response when I enter my pin. I am on the latest OnlyKey firmware (just purchased it).
This keyboard assistant usually pops up the first time you add a new keyboard. You can just accept default and then Mac enables the keyboard (or OnlyKey). If there is a physical connection issue you can see if OnlyKey shows up by clicking apple icon at top left, about this mac, system report, USB. There you should see USB devices and OnlyKey if it is connected.
If it is not connected try a different port. Try using an external USB keyboard, if that doesn’t work either there may be an issue with something on the Mac.
Thanks for the quick reply. System Report shows OnlyKey as connected. However, it still was not working. So I searched some more, and here’s what did the trick for me: reset SMC: How to reset SMC on a Mac. After resetting SMC OnlyKey became responsive and it is usable on my MacBook.