After all unsuccessful firmware update attempts with the original update file I gave up and downloaded Hanlin V5 update from here:
http://www.jinke.com.cn/Compagesql/E.../update_v5.asp
I have read somewhere in the forums that these devices are same; so I setup this update without a problem. Now the info screen of the device shows the attached image.
The device has been updated and works better;
EDIT: .txt and .doc files have still three display level; 1. the original, 2. zoom mode 3. landscape mode.
Meanwhile please note that there seems to be two differences between the updates: The Astak PDF parser and Bookshelf version is 090907, the Hanlin for both versions 090924. I don't know though if the bigger number means more developments or does it just differ because of different company names?
After the update only my welcome and shut down page has changed; other than that it's the same.
I recommend the other users, without taking any responsibility, to give it a try.
Regards,