On the bottom plug side shell pieces, there are two white and pink wires connecting the shell and the motherboard.

On the circuit board by the speaker, carefully squeeze and unplug the small white headers that connect the shell piece to the hoverboard body.

Follow the wires that connect the lights to the motherboard. Disconnect these wires from the motherboard by squeezing and pulling the small white headers.

Now you can fully remove the bottom plug side shell piece.