You layout a PCB or breadboard for the Sparkfun flavor (GND, CTS, VCC, TXD, RXD, DTR), but when you begin troubleshooting all you can find is a CH340 board (GND, +5V, TXD, RXD, DTR, +3.3V).

To refresh your memory, the A50 headset relies on a MixAmp TXD wireless transmitter, so you'll actually be dealing with a duo of updates to get your system on the straight and narrow: A50 Headset ...