https://qooah.com/2012/04/22/root-%e6%a9%9f%e6%95%99%e5%ad%b8galaxy-s-ii-%e5%8e%9f%e5%bb%a0-rom-root-%e5%8f%8a-unroot-%e6%95%99%e5%ad%b8%ef%bc%8c%e4%bf%9d%e8%ad%89%e6%96%b0%e6%89%8b%e4%b9%9f%e8%83%bd%e5%ad%b8%e6%9c%83%ef%bc%81/