Update - It's fixed!!!
For anyone else having the same issue, the fix is:
1. Put an SD card in the expansion slot - this will allow you to load and read books from it for the time being.
2. Fly to Vanuatu.
3. You will notice that the original memory has been restored and functions normally. You can remove the SD card.
I'm not sure if the fix is specific to Vanuatu, or if any French colonial island in the south pacific will suffice.
It looks like it'll keep me going until the Glo is released. There is still no sign of it in Australia yet