Hi Joe.
Are you using K60 or K61 MCU? In K61 you can do 'Secure enable' (can connect with JTag) and 'Mass erase disble' (can't connect more with JTag, but can remove flash lock with key that you prepare on secure MCU). The address for secure the flash are the same in K60 and K61, but K60 haven't 'Mass erase disble' option.
What option you use for write these
FSEC = 0x0_040C
FOPT = 0x0_040D
registers (from code, by JTag, by macro)?
Thanks.
Evgeni.