zahaizha Basically, all flashtool for any platform have capability to set the boot config of flash storage to their platform. So, even if you not set correct boot config, flashtool (include UFI) will auto set it according to the firmware patform during flashing procedure. Writing direct stock firmware in factory image in UFI eMMC ToolBox is the same prosedure doing flashing in USB mode, so "the boot config" will also auto set for you.
If the phone still dead after above procedure, you can try flash another firmware and replace other emmc chip if possible.