Look in the OP, section 1c. You may be able to root using HubCap, but this requires acquiring and using a Teensy 2 or 2++ USB Development Board, a USB-based microcontoller development system ($16 or $24, respectively).
Sorry, your Chromecast (is that even a 2012 Chromecast? I suspect it might be the newer 2015 Chromecast) fails both the checks from the opening post.My firmware version is 1.29.104827
My SN is 81301**G1D1E
It is rootable? How can I know Is It rootable?
4B21 and higher (MFG 11/2014 and newer)
-> Your Chromecast has firmware 20472 or newer and is not rootable.
Yes. See threads by Team-EurekaNot to derail this topic and go completely off-topic but... you're saying there are rooted stock images floating around? So in the event that Eureka bottoms out or something happens, there is a stock alternative? or reverting to stock?