I have a 16,2 LCD screen with the I2C backboard and the 16 pins clearly named as
VSS VDD VO RS RW E D0 D1 D2 D3 D4 D5 D6 D7 A K. A and K are the backlight.
The LCD screens I bought from Pimoroni don’t have any identfication on the pins, but there are 2 layout pictures?? on the back of the board. They start from Pin 1 at the left hand side to Pin 5, and on the right hand side it is numbered 6 7–14 15 16, but at least it is clearly marked for Pin 1 on the right and Pin 16 on the left.
I’ve tried 2 arduinos, both lcd screens, and then as a long shot changing the ATmega chip on each Arduino.
No matter what I try, it doesn’t make any difference. It lights up ok, but displays hardly anything. I uploaded the hello world sketch onto 1 arduino with the lcd attached, but you could hardly make anything out on the screen.