So I got round to upgrading the firmware to the version that handles the 4 inch display. For those who haven't done it before:
1. Get the new .bin file ready.
2. Plug in your NanoVNA and check which port it comes up on.
3. Turn the NanoVNA on and put it into DFU mode via touch menus.
4. Plug into USB port.
5. Run up NanoVNA_QT
6. Select the port under device
7. You should now see a pop up window that says found device in DFU mode, do you want to upgrade firmware (or something close to that)
8. Click [Yes], browse to .bin file, and click [OK]
9. When it's finished unplug and power off NanoVNA
10. Fit new display and power on, it should work.
I recalibrated my touch screen after the upgrade but it was close anyway so the menus worked. I removed (carefully) an SD card reader that was fitted to my display as it interferes with the fit. I must say that the larger display and font has made this very usable for me, much easier to read now.
This may inspire me to design a case for it
