Hi,
If you are still able to log into the Ubuntu system, dump the EEPROM content with
sudo i2cdump -f -y 0 0x50
Re-calculate the last (255) CRC bit, and overwrite it with
sudo i2cset -f -y 0 0x50 0xff <new_value>
If you cannot login, then manually add board info to the flashing command to bypass EEPROM reading
BOARDID=3668 BOARDSKU=0000 FAB=100
Check the detailed information in Linux_for_Tegra/tools/kernel_flash/README_initrd_flash.txt.