How to upgrade lumia640 from WP8.1 to Win10 Mobile system?

How to upgrade lumia640 from WP8.1 to Win10 Mobile system? In March 2016, Microsoft has announced the most important update in the history of WP8.1 Win10 Mobile official version began to push, now WP8.1 upgrade Win10 Mobile official version of the first complete list of models confirmed It includes 18 models including Lumia1520, Lumia930, Lumia640 and Lumia640 XL. Win10 Mobile official version of the system interface is more friendly, UI design is more beautiful, there are also good improvements in performance, it is worth upgrading.
Methods/Steps
Users need to go to the app store to download the Upgrade Advisor. The Upgrade Advisor can help check for updates that are available for your phone and free up space to start the update.

After installing the Upgrade Advisor, after opening it will automatically check for available updates.

The system will prompt for available updates, go to Settings, click on Phone Updates

Methods/Step 2
Click the download button at this time, the program will automatically start downloading updates

Please keep the network open during the download process, wait for the download to complete, click the install button

When you get to this step, click on the service agreement to continue the next update.

Methods/Step 3
The system will reboot and enter the installation phase. Just wait patiently during this process. Well, after the installation is complete, the system will automatically configure the original application and data, and wait a few minutes to experience the new system.

Notes
Keep the network unblocked during the upgrade process, and the mobile phone has sufficient power.
Other models that can be upgraded to Win10 Mobile can also be upgraded by referring to this step.