Now we should have power wired up from the Pi Cable to the powerboost 1000c. Wire #2 is actually pin 5V on the Pi, wire and #6 is ground.
Cut extra wires short
Let's go ahead and cut the wires we won't be using short. Be sure to reference the circuit diagram and double, triple check each wires. Trimming these short will helps keep everything tidy and orangized.
OK, grab the PCB and position it over the enclosure. Notice those clips on the inner walls of the enclosure? Those are going to hold the PCB in place. So position and orient the PCB with the appropriate buttons going into the right spots. The PCB needs to be inserted at an angle so that it can fit into place. Insert the PCB with the “A” and “B” button side going in first - the PCB should go underneath the clip.
Ensure the d-pad is still in place while inserting the perma-proto PCB. Carefully angle it into place. You need to fit the ninjaflex AB buttons into the cutouts, then press down the PCB to fit into place. This takes a little force and finesse. The clips are fairly strong, so you don’t need to be super gentle.
It’s starting to look finished after soldering all those wires. It’s a good idea to double check all the buttons, pins and wires to ensure everything is correct. If you got any of them mixed, it is possible to remap them in software. But make sure ground is ground and nothing is intersecting (ie, two inputs wired to a single button).
If your making the four button version, you'll need to connect Wire #3 (GPIO 2) to the button you want to be "X". Connect wire #5 (GPIO 3) to the button you'd like to be "Y".
That’s all the soldering for this project. Congratulations, you are now a master solderer! Next up, we need to add the battery and close the enclosure. Almost done!