Hi,
which device do you have? Devices with C90LC flash require swapping of the password. You can find note in reference manual like this:
"When the SSCM reads the passwords from flash memory, the NVPWD0 and NVPWD1 password order is swapped, so
you have to submit the 64-bit password as {NVPWD1, NVPWD0}."
So, it can be necessary to use password CAFEBEEFFEEDFACE instead of FEEDFACECAFEBEEF.
Best Regards,
Lukas