Step 1. Download Tecno Flash Tool & extract folder. Run SWD_AfterSales
Step 2. It will Launch Tecno Flash Tool
Step 3. On top left corner click on setting icon. Then one popup will appear, click on load, then select your firmware and click on confirm.
Step 4. Click on Play. Switch off your Tecno Smartphone and connect it by pressing both volume keys. Flashing will start in Tecno Smartphone
Video for information play here