Same problem here :
the LCD backlight is ON as soon as the power is plugged (VCC + GND)
The bottom line pixels are "visible", they disapear if I move the backlight pot
The top line is never visible
Can't display anything
Can't make the backlight flash, even with the Wire code, not using the LCDi2c lib
I'm using an Arduino Nano v3, i2C on port 4 and 5...
Can anybody help ? Is my LCD broken ?