Boot.emmc.win To Boot.img Better
: If you modify the filename, TWRP's "Restore" function might fail because the MD5 checksum won't match the new name. Only rename copies of the file intended for external use. Installation | Magisk - GitHub Pages
She sent him a one-liner:
: Tools from the Android SDK and AOSP (Android Open Source Project) can be very helpful. Specifically, mkbootimg and unpackbootimg scripts can help you deconstruct and reconstruct boot images. boot.emmc.win to boot.img
fastboot boot boot.img