Newer security patches may require authentication to flash, but for the MT6731, you can typically use bypass tools. Search for "MTK Bypass Utility" or "MTK Auth Bypass Tool." Run the bypass tool, and once it says "Protection disabled," immediately run the SP Flash Tool.
These allow your PC to recognize the MT6731 chipset in "Preloader" mode. mt6731 flash file
If you are here, you probably have a bricked smartwatch, a sluggish POS terminal, or a cheap Android phone refusing to boot. Chances are, it runs on the chipset. Newer security patches may require authentication to flash,