Hi,
Thanks for creating your own ticket.
Sorry for the issues you are having. I can help troubleshoot this with you.
I believe this is a bug with the slug conflict message.
We have a fix coming out next week, but I also have a patched version you can try now.
Please download this file:
https://www.dropbox.com/s/6l23udbep3sdae6/the-events-calendar-4.1.0.2.zip?dl=0
Then follow these steps for manual updates:
Manual Updates
That process does not delete nor change settings or events, but it is always a good idea to backup just in case.
Let me know if that fixes the issue for you.
Thanks