@droftarts , rebooting without the card did restore some functionality in DWC but has led to a whole host of new errors.
@Danal , I have already configured my Pi with duetpi, but I suspect, after reading all of your information, that something has become corrupted by updating with the SD card in the Duet slot.
Tomorrow, I'll wipe everything and reload and see if that solves the problem.
Thank you both for the assist, I certainly appreciate it.