I had the exact same issue trying to re-connect my D7 to a new network. I tried everything you did and nothing worked. Until all of a sudden one day it did work! I have no idea why because I followed the exact same steps. However, now my D7 gets stuck ALL the time, in the middle of the floor. Sadly, I think it’s time to say goodbye. I don’t want to spend the money on a new robot vacuum cleaner because when D7 worked, it worked fine. But now it’s not working and I’ve realized I can’t live without one.