Spinning wheel issue on Apple TV

Did this happen during an update? What was happening just before the spinner came on?

If it was during regular watching, then use the App Switcher (double-click TV button), to close the failing app (swipe up) and then re-launch that app. If needed, repeat for other apps that were still open (but background apps are inactive and are probably not causing this).

If it is during an update, then do you know which step of that update? You could brick your unit if this happened while it was actively overwriting system software parts. The download or verification parts can be interrupted safely (but may have to be done again). Best to consult with Apple staff then, on how to proceed.