Theres a small number of these things around that require a negative voltage on the contrast pin to get them to display. You could try a 1.5V battery with the + end to Gnd and the - end to the contrast pin or pot to test it.
Theres a small number of these things around that require a negative voltage on the contrast pin to get them to display. You could try a 1.5V battery with the + end to Gnd and the - end to the contrast pin or pot to test it.