1. Download the offline upgrade package of the corresponding model from the mobile phone service support page (http:) on the official website of ZTE. Unzip the file and release the update.zip file. Place the update.zip file under the root directory of the SD card.
2. When the mobile phone is powered off, press and hold the Volume Up key and Power key for one time, and then release the keys to enter the recovery mode. In this interface, the volume key is the menu selection key, and the power key is the confirmation key.
3. Press the volume down key to select the "apply update from SD card" option, and press the power-on key for confirmation to enter the SD card directory.
4. Press the volume down key to select the "update.zip" upgrade package, and press the power-on key for confirmation. The mobile phone upgrade begins.
5. The upgrade of the mobile phone takes about 5 minutes. Select the "reboot system now" option (as shown in Figure 3-9) in the upgrade completion interface, and press the power key to confirm that the mobile phone is restarted automatically. After the mobile phone is powered on normally, it is suggested to manually restore the factory settings (Setting - System - Reset - Clear All Data (Restore Factory Settings) - Restore factory settings) to enhance the system stability after the upgrade, and then the mobile phone can be used. The upgrade is completed.