Same problem here... It would not finish the set up via the Cortana app on my Android. After connecting to the wifi, the ring would remain white on the speaker and never finish, even though it would appear on the app that all was well. After trying everything I finally just powered it up, waited a couple mins, then stuck a pin into the tiny pin hole on the back of the speaker. l felt the internal button via the pin through the pin hole and held it compressed for about 20 seconds. While holding it in the speaker made a chime noise and it flashed a partial white circle on the top. This partial circle remained for about 5 mins or so, then it started the set up process. Via the Cortana app on my phone I did the set up and it actually worked. All functions are back to expected working order, all commands, music, outlook, news...etc... After a couple of week of fighting I am glad all is working now. But still unsure what actually caused this to happen in the first place.
I am assuming that an unplug will reboot the speaker but the pin hole button is more of a complete/total reset of the speaker.