soft brick with ayufan

[DimHummingbird]

boot0 and boot1 are not used by rk3399 cpus
It may be wise to make a copy of 1st 16M of a working (booting OK) emmc
just in case new uboot on SD doesn't work since in most cases a SD boot uses uboot from emmc
If the first 16 M goes onto a different device, the mbr will not be right

Ah, I thought the first 16M *was* mapped to boot0 and boot1.

Thank you for the reply and explanation! Even after the fact, it helps.   I'll write a blog post about this and submit to the wiki to help future adventurers.