A potential method would be to use the GPIO Jumpers
(scroll down to powering the display #3).
Your top board may not leave any GPIO exposed, if there is anywhere that gives you an output 5V you should be able to connect it to the Jumper pins of the display board.
If that doesn't work then solder a micro-USB connector onto the ends of the 5V output cable and connect that to the displays 5V input.
Building Management Systems Engineer.