Regarding the “primary SMD is corrupted!” error
The root cause was a poorly formatted /etc/nv_boot_control.conf file. Specifically the path for TEGRA_OTA_BOOT_DEVICE and TEGRA_OTA_GPT_DEVICE was wrong.
This is what the file should look like
# cat /etc/nv_boot_control.conf
TNSPEC <REMOVED AS THIS IS BOARD SPECIFIC>
TEGRA_CHIPID 0x19
TEGRA_OTA_BOOT_DEVICE /dev/mtdblock0
TEGRA_OTA_GPT_DEVICE /dev/mtdblock0
Root cause and resolution explained here: SMD Partition Corrupted after Flash - #11 by joseph.swantek