Prior to tearing it apart, I'll suggest doing the standard factory reset. If it shows the factory reset screen, chances are that enough of your system is intact to run the update process.

You need to put two files in /cache/recovery in order to do an update. If your Vox isn't booting, you'll need to pull the SD card out of it and use a card reader on a PC. You will also need to use Linux to add files to /cache/recovery since it uses a Linux filesystem. A Linux live CD will work wonderfully.

One of the files that you need to copy to /cache/recovery is called 'command', and it contains the line:

The other file is an update file from Kobo.

Once the files have been copied to the SD card, remove it from the PC, reinstall it in your Vox, power the Vox up, and it should reimage the system. Make sure the Vox is plugged into the wall while it is reimaging the system since I think it updates the bootloader and kernel too.

(Incidentally, this reimaging process works even if the version of the update file is identical to the version of the software currently installed on your Vox.)