SainSmart I2C 4 Line 20 char, Blank Screen Help

http://www.sainsmart.com/sainsmart-iic-i2c-twi-serial-2004-20x4-lcd-module-shield-for-arduino-uno-mega-r3.html

Hooked up as follows (Soldered Connections)
scl to a5,
sda to a4,
grd to grd
vcc to 5v

I found this sample code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x3F,20,4); //Addr: 0x3F, 20 chars & 4 lines

void setup()
{
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0);
lcd.print("Hello");
}
void loop()
{
}

The Backlight turns on but the screen is blank

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x3F,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display

void setup()
{
lcd.init(); // initialize the lcd

// Print a message to the LCD.
lcd.backlight();
lcd.print("Hello, world!");
}

void loop()
{
}

This sample code, makes the back light Flicker for a second then turns off and the display is blank.

I have checked The Contrast Potentiometer and got that sorted out. Though when it was set all the way up (Can see blocks) only two lines were dark. So not sure if my display is bad.

Try running this and see if it picks anything up:-
http://playground.arduino.cc/Main/I2cScanner
Are there pull ups on those data lines?

Mike,

Scanning...
I2C device found at address 0x3F !
done

Are there pull ups on those data lines?

Not sure? im new to arduino but the sketch is empty except for the code popsted in the OP

pullups, while required, is seldom a problem for a simple single slave with short wires.
The real question is which library are you running?
There was a link to a LiquidCrystal_I2C library on that page.
Are you running that one?

This issue comes quite because there is no way to make a a library
for a i2c connected lcd "plug and play" for every vendors backpack.
As a result there are many different versions of a "LiquidCrystal_I2C" library
that are different.
There are MANY threads on this.
Here are a couple of the many out there to get you started:
http://forum.arduino.cc/index.php?topic=196991.0
http://forum.arduino.cc/index.php?topic=214812.0

This is case, where understanding how the hardware is wired is needed
and then for sure you have to get all the small details correct. Otherwise it won't work.
Where most people fall down, is that they don't pay attention to the small details
or choose to not read and follow the library's installation instructions
and simply flounder in guess after guess.

My recommendation is to run fm's LiquidCrystal replacement library.
You will find references and links to it and how to get it up and
running on the backpack in the threads above.

--- bill