I think it uses a Wi-Fi connection between the device and the phone, and I also think that the phone has reconnected to CarPlay midway through, and it just says, it's downloaded the update, it says 50% of the process complete, and there's an install button.

When I click on install, it says, no device found, go to connect. When I go to connect, even when I force the phone back onto the Wi-Fi network, and it's an iPhone, by the way, I just get nothing, can't find anything, and I don't know what I'm doing wrong.

The microphone transmitter itself, by the way, has a turquoise-coloured solid light, which is what I think came on when it connected.