OK - so I went back to v126.96.36.199a. My OLED screen is working, as expected:
I then connected up the LCD screen, but it didn't seem to show any text:
Then I realised that there was very faint text when I looked at it at a certain angle:
So the issue was the contrast - so I turned the potentiometer clockwise all the way and that was much better:
I changed the firmware back to v188.8.131.52a customer firmware (LCD selected, OLED unselected) and it is working fine:
However, with this LCD I'm finding that with 'light' text has too much ghosting when it changes/scrolls, but with 'dark' text is a bit too hard to see.
I like this LCD screen physical form factor - it will probably be easier to panel mount compared to the OLED screens, but the text is no where near as good/clear as the OLED screens.
And I'm finding, after a while, the text turns to: