Apple has seeded developers with the second build of tvOS 10.2.1 for debugging on the fourth-generation Apple TV. We saw the first build of the future software update late last month. If your set-top-box is registered for preview builds of the OS, head over to Settings > System > Software Updates > Update Software and hit the download button.
So far, we’ve only been able to spot bug fixes and security enhancements in this build of tvOS 10.12.1. That said, if you spot something worth mentioning, you can tip us at firstname.lastname@example.org and @MBEDDEDMaximum on Twitter.