[Altivo]

I have removed and reinserted the SD card several times. Restarted the device without the card in, powered it off, reinserted the card, restarted the device after the card was back in place. Nothing changes.

It no longer recognizes even the books that are present on the internal memory. I can see those when I mount the device with a USB cable.

Note that I can no longer see the SD card through the USB, though it used to be visible as a second device. I think the update has completely lost the ability to detect or reference the external SD card. But that still doesn't explain why it also can't see the books on the internal memory.

By the way, the books on the external SD are still there too. Inserting them into a second Kobo of the same model that was not upgraded finds them just fine, and I can see them untouched if I insert the SD into the slot on my laptop.