Bootloader tutorial not working with certain targets

Hello,

Having needed to shift the start of the flash memory on my application, I came across your exchange. I try desperately to shift the start of the Flash to 0x00007000 but I have problems in generating the .bin file
I created this post to show the problem:
https://forums.mbed.com/t/how-to-shift-the-flash-memory-on-kl25z/17892

Thank you in advance for your help, I can not find a solution to this problem.

Sincerely, Antoine