There's 3 rows of pins to the top left of the display, if the keypad is at the bottom right.
You can find an indication of that location here (scroll down about 20 % from the top of that page)
, you'll find a picture.
You can also find the schematics
for this robot.
You need the program "eagle" to open this, open the "control board" file.
To the right you will find that these 3 connectors are in parallel, meaning they all are connected to the same signals.
It goes like this:
Pin 1 = GND
Pin 2 = 5 Volt.
Pin 3 = SDA
Pin 4 = SCL
From the pictures i could find, there's no telling which pad is 1, those pics are too small or out of focus to see.
If you have one square pad and three round ones, the square one is pad 1.
Or any other mark, marks 1.