Hi Harry,
M10AFV should be MK10DX64Vxxx, just like this picture:

For the package, you should check your hardware, If it is 48 LQFP (7 mm x 7 mm), then it is MK10DX64VLF5.
You said when you access the FTFL register, you get hard fault, please tell me which register you access?
Beside, please disable the global interrupt before your do the FTFL operation.
Wish it helps you!
Have a great day,
Kerry
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