Communicating Errors on EditText Inputs

What is the best way to communicate errors on input in editable text views.

### Behavioral Example

A hypothetical view where a user is setting up a new account, and the way a perfectly able person would interact with it.

1. User enters First Name, Last Name, Username and Password into a set of four EditText boxes.
2. User hits submit on a button.
3. User is not allowed to continue, because the password doesn't have a carrot. Stupid password security team and their insane password requirements!
4. User sees a message indicating that a ^ is required.
5. User enters a ^ into the end of the box.
6. User hits submit again and successfully creates an account.

### Accessibility Concerns

- What is the best behavior after step 2? Where should focus go? Should an announcement be made?
- How should the information gleaned in step 4 be communicated to TalkBack/BrailleBack?
- How does a user go from error condition to knowing they successfully fixed the error?