Solder socket headers to the 5x5 NeoPixel Grid BFF and solder plug headers to the QT Py ESP32-S2.

Plug the QT Py ESP32-S2 into the NeoPixel Grid BFF. Make sure that the QT Py USB port is oriented properly by referencing the USB labeling and arrow on the back of the BFF.

Insert the boards into the main case by lining up the QT Py header pins with the header pin slots in the bottom of the case.

The boards should be situated in the center of the case with the QT Py USB port accessible via the side cutout.

Close the case with the cloud lid. Make sure that the 5x5 NeoPixel Grid is centered in the cloud's cutout. 

That completes the assembly!