sudomod

I just tried to update my Circuit Sword in order to start showing the mode button hints on press, and now the HUD doesn't display at all (battery, wifi, etc). Any help would be greatly appreciated.

The only thing strange that may have occurred during the update was this error message:

Failed to stop cs-osd.service: Unit cs-osd.service not loaded.

It looks like this has also prevented the power switch from triggering the safe shutdown, so I've had to turn it off via the shutdown command instead.

Does anyone have any ideas on this? Is it possible to do a fresh install without removing other settings on the system?

If you update from an old raspbian Jessie image than that is what happens, unfortunately. The new hud drawing needs some newer libraries which are only available on Stretch (if you don't want to compile yourself). My recommendation is to do a fresh install, after backing up files and settings.