Several tech blogs have caught wind of my coverage of the eFuse added in the latest Amazon Fire TV update and have wrongly interpreted it into sensational headlines like “Amazon Fire TV Firmware Update Bricks Rooted Devices“. In an effort to get ahead of any potential panic these articles may cause, let me set the record straight by saying that rooted Fire TVs are in no risk of being bricked by Amazon’s official updates. That said, read on for a detailed explanation of the newly discovered eFuse in the Fire TV and what it means to rooted and unrooted devices.
An eFuse is a mechanism in a computer chip’s programming that allows the chip to change its behavior in response to an event. The latest Fire TV software update, version 18.104.22.168_user_514013920, has added an eFuse which appears to be triggered if you try to use an older version of the Fire TV’s bootloader in conjunction with the latest software version. When triggered, the eFuse puts the Fire TV into a low-level recovery mode. The Fire TV is not permanently bricked if this eFuse is triggered. It’s possible to recover to a fully functioning device after tripping the eFuse. If it ever becomes a common problem, you bet I’ll write a complete guide on how to recover from a tripped eFuse.
There is currently no software update, stock or pre-rooted, that will trigger the eFuse. The pre-rooted custom ROM of update 22.214.171.124 that was initialy released did trigger the eFuse, but that version has since been pulled and a fixed version without the eFuse trigger has been released. This is actually a prime example of why I like to wait a little while before posting about newly released updates and mods. A precaution I take is to wait for the brave XDA aficionados to vet the release before letting you all know about it.
This eFuse likely means that, unless somone figures out how to fully unlock the bootloader, Fire TV’s that have installed stock software version 126.96.36.199 or newer will be unable to install a custom recovery (like ClockworkMod) and custom ROMs (like Rbox’s pre-rooted updates) using the current methods, even if they get rooted. New exploits and methods can be discovered that change this in the future, but for the time being, it’s best to continue following my advice of not updating unrootable Fire TVs if you are hoping to root in the future. Or, at least do not update past 188.8.131.52. Those with rooted Fire TVs running stock or pre-rooted software currently have nothing to worry about with this eFuse. If a rooted Fire TV running either stock or custom ROMs happens to install the latest 184.108.40.206 update, it would simply lose root with no harm to the Fire TV.