Finding UDID without XCode/iTunes?

You'll have to hook it up to your Mac no matter what. Put the Apple TV into DFU mode

hold the Menu and Pause/Play buttons until the Apple TV starts flashing rapidly.

It should then appear in iTunes. Download the latest beta for the Apple TV and

holding Option click on Restore in iTunes. Point it to the beta you downloaded.

Once this is completed, it will no longer be visible in iTunes but should be visible

in xCode 7.1 beta. Go to Window->devices and your Apple TV should be there.

Copy down the UDID. Go to the developer portal and add the Apple TV to your

devices list.

The entire problem is that the cables don't work, even in DFU mode. The unit doesn't show up in iTune or in Devices (7.1 Beta 3). I just wondered if there was a way to see the UDID onscreen - some magic combination of buttons that makes is show up in a hidden menu in the settings somewhere.

No magic. Not on a TV via HDMI/Settings/About, not in System Profiler/USB, not via Wi-Fi, not on the packaging, not on the device.

I'd find yet another USB-C to USB-A cable (only).

As KMT said, no magic. If it isn't working, try a different USB port. It's very unlikely 2 new cables

both are bad. Make sure you're fully inserting the USB C end, it should click. Outside of that,

try it on another Mac with the cables you have. If it still doesn't work, it comes down to 1 of

2 possibilities. #1, both cables are bad, possible by highly unlikely and #2, the Developer Kit

unit you received is defective.

One other thing to check, open system preferences and under USB devices see if the Apple

TV is listed. If it isn't, you're back to cables or the device itself being bad.

Please make sure that you were not making the same mistake I was doing using the wrong cable.

The cable I was using was only able to supply power and not to transfer data.