1. Download the old system: Download the old system in vivo official website. After entering the old system, press and hold the power button and volume down button of the mobile phone to enter the recovery mode.
2. Select the brush package: in the recovery mode, select clear data and clear cache, then select install brush package, and select the downloaded old system brush package for installation.
3. Restart the phone: After the installation is completed, choose to restart the system, and you can revert to the old version after the restart.