Checksum passed, writing to flash...
_NAAppOffsetInFlash or _NABackupRecoveryOffsetInFlash in the linker customizatiom file is set incorrectly.
The application image must start on a sector boundary.
Failed to write flash [-8]
Also your offset for your application (see bootldr.dat) needs to be a multiple of 0x10000 (64k), you can’t start writing an image.bin in the middle of a sector of flash.