This is a followup to this question. As soon as I launch Ubuntu Core Nexus 7 Installer, check Install Ubuntu on Nexus 7 and push OK, the instalation status bar got stuck.

It lasts for quite a long time.
So does anybody have any guesses?
P.S. For those who would like to vote for closing this question as "not a real question" like it was with the one I referred to in the beginning -- please believe me that it's a real one.