Cables for LED Button
Use 2x 2-pin JST cables to connect the LED button to the QT Py.
The stock wire lengths are suffice and do not need to be shortened.
Pins on LED Button
Use the photo to reference which pins are used for the LED and switch.
The leads for the LED are just outside the gray body of the switch.
The leads for the switch are inside the gray body of the switch.
Solder Cable to LED Pins
Connect the red wire to the positive pin on the LED.
Connect the black wire to the negative pin on the LED.
Solder Cable to Switch Pins
The polarity of the switch doesn't matter here so you can solder the wires to either pins.
Here we're keeping the wiring consistent with the LED.