hello merwin,
it looks like you’re having issue as Topic 155274,
may I know what’s your commands to perform massflash, are you doing online or offline flash?
here’s offline approach for your reference,
BOARDID=3448 BOARDSKU=0002 FAB=400 FUSELEVEL=fuselevel_production ./nvmassflashgen.sh jetson-nano-devkit-mmc mmcblk0p1