Hello, @chansookang
Thanks for your reply.
From my experience, I suggest directly following the method 2 for flashing your eMMC, I understand that you have done it.
For using Flash tool, it is a little complicated. Firstly, change the default bl2_w_dtb.s32-sdcard, derived only the data from 0x1000 to the end and save it, say derived.bl2_w_dtb.s32-sdcard.
Then use the flash tool to flash the newly generated image with the offset 0x1000 to have a try.
BR
Chenyin