If WordPress Login fails and you are redirected with a supposed blocked cookies error
This famous login redirection (assuming that you use the correct password and username) can have a lot of causes.
Usually the problem is with some plugin that needs to be deactivated, a theme with strange code that refers to hidden cookies, absence of certain definitions in wp-config, etc.
In my case the problem was in the cache and cookies of my browser(s).
I emptied the cache and deleted all cookies, then WordPress accepted my login credentials and I was able at last to enter the dashboard of my blog!