@Kiwisaurus : Let me ask it again, did you read the previous answers?
First we downloaded the Mark4 4.9.11311 firmware update and applied it to her Mini (unpack the .zip file on my computer and copy both files and the directory into the .kobo directory on her Mini, safely eject it and let the firmware update happen). We then downloaded the Mark6 4.10.11655 firmware, unpacked the .zip file and copied only the KoboRoot.tgz file to the .kobo directory on her Mini. After safely ejecting, it updated
Everything you need to know is there