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An eFuse, or electronic fuse, is a microscopic fuse put into a computer chip that can be triggered to blow in order to permanently change the circuitry of a chip. While eFuses have other uses, they are most commonly used by hardware manufacturers to prevent older software from running on the device. The older software expects a certain number of eFuses to be intact when the device boots, so blowing an eFuse makes older software incompatible with the device.

Amazon has blown eFuses on Fire TV devices in the past as a way to seemingly prevent newer devices from taking advantage of older software exploits that allowed the device to be rooted or allowed the bootloader to be unlocked. This latest blown eFuse seems to be a way to keep devices on the new Fire TV interface, but we’ll likely never know if that’s actually the reason. Regardless of the motivation, the fact is that a Fire TV Stick 4K that updates to the stock version of Fire OS 6.2.8.0 will not be able to downgrade, even if it is later rooted.

Rbox, a developer who has been active among the Fire TV modding community for years, has determined that Amazon has chosen to blow an eFuse with Fire OS v6.2.8.0 on the Fire TV Stick 4K to prevent downgrading. He says a script was added in a previous Fire TV software update that did nothing, but that script was activated in the latest software update to blow an eFuse.

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Posted by Elias Saba on April 5, 2021

Code:
https://www.aftvnews.com/amazon-blows-efuse-on-fire-tv-stick-to-prevent-downgrading-to-old-interface/?fbclid=IwAR27qFKfiR8mUVq_zIizbOOIGo-gA446DUB-qOo78WXahbjxsgOPBBKma9U