I don't think I have a solution for you.
I might try allot of things, maybe start with a other browser.
Maybe you can reset the login or use forgot manager login?
Try the forum for solutions, google "modx lockout evolution" or smt.
What version did you upgrade?
Evolution user, I like the back-end speed and simplicity

I'm freestyling here, maybe you have special characters in your password?
http://tracker.modx.com/issues/9870
Evolution user, I like the back-end speed and simplicity

Solved with help from the MODX-Team:
I don't know why, but my admin user had "allow_manager_access" set to 0 in table "modx_user_settings". Setting it to 1 in phpMyAdmin solved it.
Easy if you know what to look for.
Thanks to everyone!
Jörg