For now, he should use his username. It was found that the issue is the system expects an exact match on the email address used in the login form and on the account, case included. So one change in the case will prevent the sign in.
It will probably be fixed soon.
Yes, he tried that... He can sign in using his Username, but not with his Email. He has been using the same email since he opened the account. I have no problem with my account..