I progressed all the way through the startup wizard on my Mark 1 to the point where Mycroft wanted to register itself. I had issues registering an account at home.mycroft.ai (now resolved), but then I had turned off Mycroft, so I powered it back up again.
When connected via the MYCROFT WiFi access point, it wanted me to select a WiFi network to connect to and supply a network for; my WiFi network was already connected, so Mycroft didn’t present me with a box to put the password in. That box seems to also comes with the “next” arrow, which was not displayed on my WiFi network. As a result, I could not proceed any further.
The workaround was to reset Mycroft and start from scratch. However, if there were a “proceed” arrow on any existing WiFi network for which it had a working key, I could have continued from there.