Secure the breakout to the third helping hands and position it close to enclosure. Heat up the pins on the breakout board with the soldering iron and insert the wire. You’ll want to do this pretty quickly, about 5 seconds for each connection. Blue to GND and green to EN. You can skip the red wire, we don't need it.
It's a good idea to thead the holes on the PCB to make it easier to mount to the enclosure. #4-40 3/8 flat phillips machine screws work best.
With the wires on the powerboost soldered, you can release it from the third helping hands. It’s a good idea to tuck the wires underneath the board before mounting it. Position the breakout over the bottom enclosure with the USB port facing the cut out. You’ll want to tuck the three wires from the slide switch underneath the PowerBoost 1000c. The stand-offs should give you enough clearance.
You’ll need #4-40 ⅜ Phillips flat machine screws to mount the board to the enclosure. Hold the breakout board in place while you insert and fasten two #4-40 machine screws into the enclosure.
Plug in the JST cable from the rechargeable battery into the JST port. Flip the slide switch on to test if the circuit is working. The blue LED should turn on, indicating the battery is charged and ready. If everything lights up, disconnect the battery from the breakout board. If not, double check your wiring.