Connect to ItsyBitsy M4
Solder the 3-wire cable from the rings to the pins on the bottom of the ItsyBitsy M4. Connect ground wire to the ground(G) pin, data in wire to pin #5 and 5V wire to Vhi pin. The Vhi pin is ideal for powering NeoPixels through USB or battery.
Wire Lipo Backpack Wires
Solder the two wires from the Trinket/ItsyBitsy Lipo Backpack to the BAT and USB pins on the ItsyBitsy M4. Check the continuity with a multi-meter to check which wire is connect to the BAT and USB pins.
Carefully install the ItsyBitsy M4 into the enclosure. Insert the PCB at an angle so one side is under the clips. Press the PCB into the case to snap fit it into place. Slide the PCB down so it's flush with the case.