completely locked out of email after yahoo migration fails with "something went wrong"

After reading the notice and FAQ about the migration, I decided to go for it. Clicking the link in the Comcast email took me to login.yahoo.com, where I entered my comcast.net email address. This redirects to login.xfinity.com, which tells me I am already signed in:

Clicking "Continue" goes to a Comcast-hosted "Yahoo Migration Notice Page". Clicking "Continue" there returns to login.yahoo.com, where I am prompted to secure my account by changing my password.

Clicking the "Yes, secure my account" button takes me to a page to enter a new password, and after doing so and clicking Continue, I get the message:

"Uh oh, looks like something went wrong. Please try again later."

So, I did try again the next day without success. Since this was all on my iPhone, I tried from Firefox on my mac, and from Edge on my PC, all yielding the same message.

Attempting to log in to xfinity email just gives me a message "Your Comcast.net email account is accessible at Yahoo Mail":

As of now, I am completely unable to access my email account. Any Ideas?

Thank you!