[afainber]

Onyx themselves do not distribute updates. They are developing new features and fixing bugs and these changes are packed by the vendors who sell Onyx devices (along with their own additions/fixes to their own software) and the complete new firmwares are then pushed by these vendors to their customers.

This particular thread is dedicated to the Onyx T68 devices sold by Booxtor on ereader-store.eu, however Booxtor published a guide for how you can install his firmwares on T68 devices bought from different vendors (who have their own updates once in a while).