This is simply tips for replacing emmc in any Mediatek platform.
Only write preloader via Factory Image tab.
After that, resolder emmc to board, and connect USB to PC.
If emmc is good, resoldering is ok, especially emmc with lpddr(emcp), device must detect as Preloader Vcom Port in Device Manager.
But, if device still detect as MTK USB Port, means preloader not work, emmc maybe damage, or your resoldering ic is not good.