After vivox7plus was downgraded, the phone flashed back and the SMS stopped running.

This situation indicates that there may be a problem with the mobile phone system. Due to the loss or damage of system software, some functions can't run normally.

This problem can only be fixed by brushing the full version of the system package. Users are advised to try it.

If you have the ability, you can try to brush the machine yourself, but it is safer and more assured to leave it to the local after-sales outlets.