Stupid me flashed this without reading the whole thread for possible issues ... I also got the "First block failed verification..." error and now my Chromecast (1st gen) is stuck on the "chromecast..." black screen and I can't ssh or telnet to it.
Since I was trying to get as close to non-rooted as I can I might as well unroot. Is there a way to trigger it to reflash the Google OTA? Or how would I do it? I rooted this years ago and barely succeeded so it might just be easier to go and buy a new one if extra hardware is required to unroot.
Edit: I can ssh and also get the "SETUP FAILED: Unsupported Mode! This version of Flashcast can only be ran from the recovery parition of the Chromecast."