Blizzard Battle.net App Stuck in Chinese

To resolve the issue follow the steps below to set up a new administrator account for the computer that does not have the language pack installed. 

New Administrator Accounts

Windows 10

1. Click Start.
2. Type Add User.
3. Select Add, edit, or remove other users.
4. Click Add someone else to this PC.
5. Click I don't have this person's sign-in information.
6. Click Add a user without a Microsoft account.
7. Set the User Name as Test, click Next.
8. Select the account Test. Choose Change account type.
9. Choose Administrator from the dropdown, click OK.
10. Right-click on Start.
11. Select Shut down or sign out > Sign out.
12. Login to Test.

Once logged in, run the Blizzard Battle.net App.

Mac

1. Click the Apple Menu and select System Preferences.
2. Click Users (Users & Groups in 10.7).
3. Click Add (+) below the list of accounts.
4. Choose Administrator from the New Account pop-up menu.
5. Enter a full name for the account. Note: An account name is generated automatically. If you want to use a different account name, enter it at this step. After the account is created, you can’t change the account name.
6. Enter the account password in the Password and Verify fields, and then enter a hint to help you remember the password.
7. Click Create User.