lcd 1602A with i2c adapter (mjkdz) don't write caracters [solved]

16x2 modules commonly have headers at the top left of the display.
Other modules have headers at bottom right.

I suspect that this mkjdz adapter is designed for bottom-right modules.
Whichever style of adapter / module is used, you can stop short-circuits by slipping paper or thin plastic between the two pcbs.

Hey-ho. The OP has got it working now.

David.