Hi Alan, I assume you have a monitor connected to you Pi? You shouldn't need this or a keyboard.
Since you have edited files in response to th Pi forum, I would reformat the SD card, and copy new files to it. Put it in the Pi and boot it up. Keep an eye on you tablet or phone for a PilotAware hotspot.
Connect to the hotspot and open 192.168.1.1 in a browser, where you should be able to enter your new key.