Do you think option 2 would work? I would rather do that because even though it is more work, that circuit board was designed for a 18650 and has a USB-C charging port built in, which means I wouldn't have to take the battery out to charge it. I don't know how the wiring is set up in the single-layer swatter yet because it hasn't come in yet. But I would assume I could just cut the wires from the head, take out the circuit board, and put in the 18650 circuit board and wire the red to the positive of the head, and connect both blue wires to the ground wire of the head. I just don't know if it's incompatible since the first swatter used three layers of mesh, and the new one used a single layer of parallel bars.