Graphic LCD 128x64 STN LED Backlight not working

Hello everyone.

I just finished soldering my lcd backpack on my 128x64LCD

LCD Graphic LCD 128x64 STN LED Backlight - LCD-00710 - SparkFun Electronics
Serial BackPack SparkFun Graphic LCD Serial Backpack - LCD-09352 - SparkFun Electronics

All I see when I try to use it from my DUE is those black stripes :frowning:

Also the docs aren't clear:

void setup()  
  pinMode(13, OUTPUT);
  delay(500); // wait for display to boot up
  Serial.write((byte)0x7C); //clear the display
  Serial.write((byte)0x00); //

void loop() // run over and over
  digitalWrite(13, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(13, LOW);    // turn the LED off by making the voltage LOW

If your backlight isn't working, what are those bright bits around the edge of the display?

Black stripes were coming from a bad solder.
The LCD wasn't working because you need to wait at least 1000 before sending anything to the serial port
otherwise will start parsing serial data from random position, doing weird things.