Account blocked / http 400 error

Do you login to AWS Console with a username & password (& MFA)? Or does your university login credentials automatically log you with single-sign-on in as a federated user in Active Directory (or whatever identity provider is used at your site).

If it's the latter there may be something locally that's changed. You were away for a week, so has a password expired or an account become locked?

If it's the former, and this really is your account with no relation to your university, then contact AWS directly and they can help you out. If you can't even login to the console to raise a support ticket then try this https://support.aws.amazon.com/#/contacts/aws-account-support