You must download the exact "Scatter-based" Stock ROM made specifically for your device model. Flashing firmware meant for a different model can permanently hard-brick your hardware. Step-by-Step Tutorial: How to Use MTK Flash Tool v5.1420
Can restore devices that have become unresponsive due to software corruption or failed updates. mtk flash tool v51420 top
This is the most critical step. Without the correct drivers, your PC will not detect your phone, and the SP Flash Tool will be unable to communicate with it. You must download the exact "Scatter-based" Stock ROM
A typical firmware restoration using v5.1420 proceeds as: mtk flash tool v51420 top