Previously root was only working on very old builds, but it looks as though a new vulnerability has been found and root is not possible on build 17977. Google Chromecast Rootable Once Again! Spoiler Personally, it seems a little more bother than it's worth. You need to purchase something called a teensy (costs around a tenner), a powered USB OTG Cable and an external flash drive. I'm normally very pro root, but given the pre-requisites here and the fact that Chromecast does pretty much all I need it to anyway, this isn't for me.