Thank you for unlocked firmware for Redmi 3s that allows us to change eMMC chip only.
There are also some FACTORY firmwares for other Xiaomi phones which includes unlocked emmc_appsboot.mbn, but there is nothing for quite popular Xiaomi Redmi Note 4x model. For now it's impossible to change eMMC on this phone. We have to swap a pair (eMMC + CPU) from another PCB.
Is there a chance you will get unlocked bootloader files for this phone so we could replace eMMC, patch boot.img and bring this phone back to live?