Hi, for LCD2004, if you get the backlight and two rows of rectangles as the picture shows, it might be the wrong settings of firmware.
For LCD2004 you should delete the “//” from this line of the code“//#define REPRAP_DISCOUNT_SMART_CONTROLLER”; And add “//” in front of the code” #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER”, because this line is for LCD12864. Then upload the firmware.
Before delete the “//”
// The RepRapDiscount Smart Controller (white PCB)
//
http://reprap.org/wiki/RepRapDiscount_Smart_Controller
//#define REPRAP_DISCOUNT_SMART_CONTROLLER
// The GADGETS3D G3D LCD/SD Controller (blue PCB)
//
http://reprap.org/wiki/RAMPS_1.3/1.4_GA ... with_Panel
//#define G3D_PANEL
After delete the “//”, it should be like this:
// The RepRapDiscount Smart Controller (white PCB)
//
http://reprap.org/wiki/RepRapDiscount_Smart_Controller
#define REPRAP_DISCOUNT_SMART_CONTROLLER
// The GADGETS3D G3D LCD/SD Controller (blue PCB)
//
http://reprap.org/wiki/RAMPS_1.3/1.4_GA ... with_Panel
//#define G3D_PANEL