[Update: Fixed] Android TV 12 preview builds for ADT-3 can’t be flashed

Ben Schoon | Feb 24 2021 - 8:43 am PT

Way ahead of what anyone expected, Google debuted the first preview for Android TV 12 last week right alongside builds for smartphones and tablets. Frustratingly, though, a glitch is preventing developers from flashing Android 12 preview builds on ADT-3.

Android TV generally lags way behind smartphones when it comes to major platform releases. For example, the brand new Chromecast with Google TV ships with Android 10, and Android 11 was never actually shipped to any retail Android TV devices outside of Google’s own developer device. That’s why it was such a surprise to see Android 12 made available for TVs so quickly, but it’s a great sign of the company’s commitment to the new Google TV platform.

The problem, though, is that many developers currently have no way of accessing Android TV 12 on ADT-3, the only device that is currently supported for flashing the update.

Apparently, the most recent version of Android 11 available to ADT-3 breaks the ability to allow OEM unlocking on the device. Hidden in the developer options, the OEM unlock toggle allows users to unlocked the bootloader of ADT-3 from a computer using adb/fastboot commands. Without that toggle flipped on, the fastboot flashing unlock command returns the error FAILED (remote: ‘unlock_ability is 0, can not unlock’) and fails to unlock an ADT-3’s bootloader. The issue has already appeared on the Google Issue Tracker.

In theory, developers with an ADT-3 that is on an older version of Android or that already have an unlocked bootloader should be able to install the Android 12 previews, but we can’t verify that since, well, we can’t unlock the bootloader on our own ADT-3 unit.

Askey, the company that produces and sells ADT-3 for Google, confirmed the issue in an email, saying that the company is working with Google on the issue. Currently, the company’s suggestion for getting Android 12 on ADT-3 is to wait for Google to release the final version. Not ideal, obviously.

Google tells us that they are aware of the problem and currently working on a fix.

Update 2/24: Google has fixed this issue, offering new builds of Android 12 for both Android TV and Google TV. The company explains that the Settings app on ADT-3 was using an outdated implementation of OEM Lock that used “the original PersistentDataBlock design instead of the OEM Lock HAL.” An OTA update will roll out to ADT-3 units to fix the issue on Android 11. In the meantime, Android 12 preview builds can be installed on ADT-3 using the flash-all.sh script. Once run, this will permanently fix the problem on that device specifically. We’ve tested this out ourselves and it was successful.