Today I can log in, with my new password. I quickly did the cancellations and new bookings I needed to do.

For my profile, the new credit card I had saved a few times before as the default (when making bookings), is still not saved. I added it in and saved as the default in my profile. Hope it stays.

The Marriott system is awful, to be locking customers out for days, and the reason is still not clear. There is also customer service fail, when calling in for help. (There was no more response to my email)