Be gentle, I'm a little new to all of this When I run the HelloWorld example program from the library, the backlight comes on and I can change the color of the backlight with the buttons, but I'm not getting any text. I went through each solder joint and they all seem solid.
The solder joints on the header pins of the display board look very good. The one on the header pins of the shield look a bit suspicious. They are smooth and shiny, which is good. But they appear to be balled up around the pin and may not have flowed well onto the surrounding solder pad. The ideal joint cross-section is concave as in the diagram below.