We are now into territory where I cannot provide a lot of help. We will need to wait for someone else with a v6 to chime in. I would check that the screen is plugged into the Raduino board correctly, as well as the encoder. Also check the solder connections on the encoder. There should be a ground connection on the center pin of the 3 pins side.
You could try testing the encoder out of the rig with an ohmmeter. Should be able to see off and on states as you turn the encoder for each of the two inputs. This could also be done with the power on, provided you can get to the contacts to measure the voltage. It should vary between 0 and roughly 5 volts.
I have no experience with the touch screen on the v6. The touch screens that I am using on my v4 and v5 rigs are Nextion with a single serial connection and a built-in controller.
One more suggestion; do not post a new topic if you are still working on the same issue. For those like me, we read through the history of the topic before trying to answer the question or provide an opinion. If you post with a new topic each time that history is hard to follow. For any follow-on comments, just reply to this topic.