Two Nitrokey Passkeys Dead

Last year I bought two Nitrokey Passkeys for their FIDO2 functionality. However, both are now dead: I plug them into the computer and they show a permanent yellow light and refuse to respond to any commands. The dmesg logs show nothing when I plug them in, and they are not listed under lsusb either. Is there any way to debug this, or are they simply broken?

You should rather reach out to support directly through email regarding this. They may help you fix problem or even offer a replacement.