This could be the schematic: https://wiki.52pi.com/index.php/Raspberry_Pi_Super_Capacitor_RTC(English)
The square solder pad is always pin 1. I think that is 3.3V or 5V (the DS3231 works both with 3.3V and 5V).
Pin 1 (square) = 5V or 3.3V "+"
Pin 2 = SDA "D" is data
Pin 3 = SCL "C" is clock
Pin 4 = not connected "NC" is Not Connected
Pin 5 = GND "-" is GND
Can you verify the GND ? If that is okay, than you can connect the module and run a I2C Scanner sketch to see if it is detected.