ok, given that you received a used device in an unknown state, I think wiping everything and starting fresh would be the best bet. Here’s what I’d recommend doing:
- Download latest PureOS ISO and write to USB
- Boot PureOS USB via Pureboot menu: Options/Boot Options/Boot From USB. then select USB device from list (usually /dev/sda1 or sdb1)
- Do a clean install of PureOS, wiping the internal storage, and using the default partition setup etc.
- Before rebooting, format the Librem Drive (ext4 or fat32) so that Pureboot can save the keys to it later
- Reboot, and you should be prompted to perform an OEM reset. Do so.
- Reboot, create the new HOTP secret when prompted, then defaul boot should work