Vivo Y91i (1820) formatted user data successfully done by Hydra Tool
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1. Run Hydra MTK Tool.
2. Choose Brand and Module.
3. Go to "Service"--> "Tool".
4. Choose "Ultra Power Option".
5. Choose "Erase User Data" from Method / Option.
6. Click on "Execute".
7. Connect Device to Computer using USB Data Cable.
8. Wait until the process is completed.
2. Choose Brand and Module.
3. Go to "Service"--> "Tool".
4. Choose "Ultra Power Option".
5. Choose "Erase User Data" from Method / Option.
6. Click on "Execute".
7. Connect Device to Computer using USB Data Cable.
8. Wait until the process is completed.
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