[Upgrading, Modifying and Unlocking] sd_shadow:
Using fastboot.exe with MediaTek Devices

There's a special flash tool for MediaTek Devices

SP Flash Tool see post #24

It appears for a/b slot devices, slot a should be set as active.

Like this

fastboot set_active a

Example of full command for Motorola MediaTek devices

fastboot devices
fastboot set_active a
fastboot getvar max-sparse-size
fastboot oem fb_mode_set
fastboot flash gpt PGPT
fastboot flash preloader preloader.bin
fastboot flash lk_a lk.img
fastboot flash lk_b lk.img
fastboot flash tee_a tee.img
fastboot flash tee_b tee.img
fastboot flash md1img_a md1img.img
fastboot flash md1img_b md1img.img
fastboot erase nvdata
fastboot flash spmfw_a spmfw.img
fastboot flash spmfw_b spmfw.img
fastboot flash scp_a scp.img
fastboot flash scp_b scp.img
fastboot flash sspm_a sspm.img
fastboot flash sspm_b sspm.img
fastboot flash cam_vpu1_a cam_vpu1.img
fastboot flash cam_vpu1_b cam_vpu1.img
fastboot flash cam_vpu2_a cam_vpu2.img
fastboot flash cam_vpu2_b cam_vpu2.img
fastboot flash cam_vpu3_a cam_vpu3.img
fastboot flash cam_vpu3_b cam_vpu3.img
fastboot flash vbmeta_a vbmeta.img
fastboot flash vbmeta_b vbmeta.img
fastboot flash oem_a oem.img
fastboot flash oem_b oem.img
fastboot flash logo_a logo.bin
fastboot flash logo_b logo.bin
fastboot flash boot_a boot.img
fastboot flash boot_b boot.img
fastboot flash dtb_a dtb.img
fastboot flash dtb_b dtb.img
fastboot flash dtbo_a dtbo.img
fastboot flash dtbo_b dtbo.img
fastboot flash system_a system.img_sparsechunk.0
fastboot flash system_a system.img_sparsechunk.1
fastboot flash system_a system.img_sparsechunk.2
fastboot flash system_a system.img_sparsechunk.3
fastboot flash system_a system.img_sparsechunk.4
fastboot flash system_a system.img_sparsechunk.5
fastboot flash system_a system.img_sparsechunk.6
fastboot flash system_a system.img_sparsechunk.7
fastboot flash system_a system.img_sparsechunk.8
fastboot flash system_a system.img_sparsechunk.9
fastboot flash system_b system_other.img_sparsechunk.0
fastboot flash system_b system_other.img_sparsechunk.1
fastboot flash vendor_a vendor.img_sparsechunk.0
fastboot flash vendor_a vendor.img_sparsechunk.1
fastboot flash vendor_b vendor.img_sparsechunk.0
fastboot flash vendor_b vendor.img_sparsechunk.1
fastboot erase userdata
fastboot erase metadata
fastboot oem fb_mode_clear
fastboot reboot

If you use the online flashfile.xml convertor you will get something like this.

Which is missing many of the slot b commands.

fastboot getvar max-sparse-size
fastboot oem fb_mode_set
fastboot flash gpt PGPT
fastboot flash preloader preloader.bin
fastboot flash lk_a lk.img
fastboot flash tee_a tee.img
fastboot flash md1img_a md1img.img
fastboot erase nvdata
fastboot flash spmfw_a spmfw.img
fastboot flash scp_a scp.img
fastboot flash sspm_a sspm.img
fastboot flash cam_vpu1_a cam_vpu1.img
fastboot flash cam_vpu2_a cam_vpu2.img
fastboot flash cam_vpu3_a cam_vpu3.img
fastboot flash vbmeta_a vbmeta.img
fastboot flash oem_a oem.img
fastboot flash logo_a logo.bin
fastboot flash boot_a boot.img
fastboot flash dtb_a dtb.img
fastboot flash dtbo_a dtbo.img
fastboot flash system_a system.img_sparsechunk.0
fastboot flash system_a system.img_sparsechunk.1
fastboot flash system_a system.img_sparsechunk.2
fastboot flash system_a system.img_sparsechunk.3
fastboot flash system_a system.img_sparsechunk.4
fastboot flash system_a system.img_sparsechunk.5
fastboot flash system_a system.img_sparsechunk.6
fastboot flash system_a system.img_sparsechunk.7
fastboot flash system_a system.img_sparsechunk.8
fastboot flash system_a system.img_sparsechunk.9
fastboot flash system_a system.img_sparsechunk.10
fastboot flash system_b system_other.img_sparsechunk.0
fastboot flash system_b system_other.img_sparsechunk.1
fastboot flash system_b system_other.img_sparsechunk.2
fastboot flash vendor_a vendor.img_sparsechunk.0
fastboot flash vendor_a vendor.img_sparsechunk.1
fastboot erase userdata
fastboot erase metadata
fastboot oem fb_mode_clear
echo -----------------------------------------------------------------------------------------------
echo English - Process concluded!
echo Português - Processo concluído!
echo English - Press any key to restart the phone!
echo Português - Pressione qualquer tecla para reiniciar o celular!
echo -----------------------------------------------------------------------------------------------
pause
fastboot reboot
exit