NOTE: You can upgrade your phone by Local Update method without unlocking your phone. The method suits for the situations listed below for sure: Update to EU Version ROM from EU versioin ROM, Update to US version ROM from US version ROM. If you encounter the issue that the reboot page keep loading for a long time after flashing, you can choose to wipe all data via entering Recovery Mode. You can turn off your device and then hold both Volume+ button and Power button at the same time to enter Recovery Mode.
Before Updating make sure your phone's battery is above 35%.
STEP 1 Download the latest ROM. There is no need to do it again if you’ve already downloaded the latest ROM file.
STEP 2 Connect your device to the Windows PC/laptop via a micro USB cable, and copy the ROM file"updatepackage.zip" downloaded in Step 1 into the "Internal shared storage” root directory. If the file is not named as updatepackage.zip , please rename it to updatepackage.zip.
Step3: Copy “updatepackage.zip" into Internal shared storage root directory.
Step4: Find the “System Update” APP on mobile desktop and click on the three dots in the top right corner.
Step5: Click“Activation Code” 5 times
Step6: The phone will automatically detect “updatepackage". Choosee install now. Your device should automatically boot to the new version when the update is completed.