Yes, my Gen3 does not recognize SD cards and yes, I tried different capacities and manufacturers, and this was from the get go, when I received the replacement for my "broken screen" Gen3 at a cost of over $200. At that point I emailed Booken, but I decided to live without SD card, it was just too much bother. However, when the update came out, I wanted to install it, so after over two weeks of yelling and screaming at Booken, I got this email explaining how to flash update sans SD. Note - this is for Gen3, so you might want to check with them if the same thing would work for Opus (I imagine the name of the kernel would be opus_upgrade). Here it is:
We apologise for the delay of our answer.
Our technical team has worked on a way to upgrade the Cybook without using a SD card.
First of all you need to download the firmware upgrade and change the name of the update kernel file for: cybook_upgrade
Then, we invite you to follow this procedure:
1) The Cybook has to be well charged
2) Connect the device to a computer via the USB cable
3) Turn it on; the connected screen appears
4) Copy the Cybook_upgrade at the root of the Cybook (beside the folders “ebooks”, “pictures”…)
5) Once the file is in the Cybook, take the USB cable off. The installation of the firmware upgrade has to begin.
6) After about 2 minutes the light of the device flashes, wait a little bit.
7) Push the reset button (the device turns off and the light as well)
8) Plug back the USB cable and switch the Cybook on
9) Access the internal memory of the Cybook. The Cybook_upgrade file must have disappeared. If it is not the case, delete it.
10) Disconnect the Cybook, wait until the library appears
11) Congratulations! Your Cybook has been upgraded.
12) In order to check the version of the device: Menu>Advanced>About
Please let us know about the result.
Bookeen Support Team
Bookeen - www.bookeen.com
Ubibooks - www.ubibooks.com
This worked for me.