This quote from the AT&T forum ...
@TryGmail so I got it fixed.... I chatted with customer support and they were great. They reset my account and sent me a temp password. It didn't work the first time, but the second time we finally got it to work.
It looks like the error "Code 205.2 [LU003]" basically says that you've been locked out of your account for 24 hours because of excessive failures.
So yeah, I think you need to either wait 24hrs for the timer to expire so you can try again, or find someone in AT&T customer support that is willing to reset the account and not make you wait.
This all seems like a really bad policy ... e.g. I could just try (and fail) to login to someone else's account and lock them out of it!?
Anyway, suggest you try again to get a customer support person to do their job and not assume it will fix itself in 24 hours. That they need to reset the password and let you in right away
Oh, and then eventually move your email to another provider. AT&T/Yahoo are basically idiots.