[rashkae]

You don't need to register to update the firmware, so I would suggest doing that first.

Registration can be bypassed with:
sqlite3 KoboReader.sqlite "INSERT INTO user(UserID,UserKey) VALUES('1','');"

Since userID and UserKey are the only fields that actually nee to be given a value, this will work regardless of the number of other fields added.

However, that's not needed any more.. With recent version of the firmware (4.31 or newer), it's far more productive to use Sideloaded mode.

Edit /.kobo/Kobo/Kobo eReader.conf

And in the [ApplicationPreferences] section, add a line:
SideloadedMode=true

Important: On Windows, you need a text editor that will preserve Unix Line ending, I suggest downloading and installing Notepad++ for this.