I bought a Unicom card from Taobao, and the seller said to send MMCZ# and add a new password to 100 10 to modify the password, but I sent it, and the sending failed, leaving the balance.

What the seller provides you is a password reset instruction, and the password modification instruction is to send "40 1" or "MMXG# old password # new password # new password" to 100 10.

Because you need to receive the verification code to reset the password, you can't reset the password if there is arrears.

It is recommended to pay the phone bill before changing the password or resetting the password.

Before paying the arrears, you can contact customer service or go directly to the business hall to check the phone bill balance.

You can modify the service password in the following ways:

1. Log in to the online business hall/homepage, and click Self-help > Business > Service Password Management > If you modify the service password, you can modify it;

2. After logging in to the client of the mobile phone business hall, click Handling > Business Handling > Service Password Modification: enter the original service password and the new service password to modify the password;

3. Send the short message "40 1" or "MMXG# old password # new password # new password" to 100 10 to modify the secret service password for free.