ClusterBox BMC broken, firmware download needed

I made the mistake of trying to do an opkg upgrade on the MIPS BMC, which appears to have installed a default /etc/sudoers file which no longer contains the mixtile user - so I’m a bit stuck.

I’ve tried the WebUI Reset option, but that seems to just sit saying “The system is erasing the configuration partition now and will reboot itself when finished” forever.

… so I’m hoping that I can still reload a firmware image via the WebUI to return to Factory Defaults.

Does anyone have any further suggestions about how I can fix this, and ideally a link to the original BMC firmware image to reload?

Progress - I can login via ssh as root stil. /etc/sudoers has changed, but not in any significant fashion. However when running, say, sudo opkg list-upgradable as the mixtile user (which used to work), I now get a password prompt and then the message “mixtile is not in the sudoers file.” (which is true).

Perhaps the default contents of /etc/sudoers.d has been lost?