Yesterday, Microsoft pulled the latest Windows Technical Preview for phones (build 10051) for the Lumia 520, and its siblings including the Lumia 521, 525, and 526. The reason being that once users upgraded to Windows 10 and then tried to revert back to Windows Phone 8.1, those device would get bricked.
Microsoft has today issued a response on the Microsoft Answers forum detailing the underlying issues. While the company is still investigating, it has determined ones of the issues that is causing devices to get bricked. The software giant claims that the aforementioned devices were rejecting the recovery images being flashed due to data writing size and speed.



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