I attempted flashing my CP-71WA to the latest firmware update from January 2026 here.

It refuses to update. Tried 4 different USB drives. The unit recognizes the drive, shows me the new firmware version to be installed but as soon as I tap update on the New Firmware Version screen, the display goes blank while the LEDs remain illuminated. After that, nothing happens. I've waited 15+ minutes. As soon as the screen goes blank my thumb drives indicate they have power but are not being read.

EDIT:
I found a few comments on reddit in the last 3 months with a similar experience. One of them said they eventually got it to work with a different USB drive so I tried a few more. Eventually one of them finally worked.

 

Some stereos you need it, some just use GPS from the phone but can be less acurate depending where you keep your phone. With the GPS antenna on the radio, you can keep your phone in your pocket, center console, etc... and not have to worry about degraded GPS signal.

 

Thanks. I updated my original post to account for the volume knob on the CP-71WAK.

 

I linked to the literal design from Apple.

It's not stereo dependent.

Wireless CarPlay requires using the GPS from the head unit.

 

I’m using wireless CarPlay with my CP-71W and I don’t have the GPS antenna connected to the stereo and my maps works just fine.

 

Then you are lucky enough the GPS module in the head unit works without the antenna. Whether the antenna is connected or not the head unit has a GPS module.