Sorted, many thanks. Not exactly sure what I did differently this time but I ended up with a different result - PanelDue5i is working!
When I removed the unit I checked the cable and during my belling out a crimp popped out, the connection looked fine but when I tested it it showed open circuit, 50/50 chance for where the bad end was and I lost, it was the end on the motherboard end. Two crimps later and a firmware update and all good.
Tomorrow is calibration of extruders and fun with bed levelling.
It's a little unusual that it is getting messages to display but also still showing connecting.
When you have your hardware connected please share some more details like the results of sending M122, M98 P"config.g", your entire config.g, and how you have the panel connected, and ensure the baud rate in config.g and the panel match.
@Bluemalu I've asked for this information a few times now.
Just make sure the ribbon cable is connected and configured to pass power from the Pi to the Duet and you should be ok. But without Vin you can't test much more than just the basic communication (if you have Vin connected then you might want to leave the jumpers at the default settings which feeds power from the Duet to the Pi)