I would strongly recommend updating FW to 3.4.2, then 3.4.3. This will enable network, otherwise certificates are too old.
Then do JB from NiLuJe’s Snapshots (stickied to the Kindle Dev Corner), then install MKK, then KUAL, then find koreader on github and install kindle-legacy version.
This is the best thing you can (painlessly) do to enjoy K3!