Hello Ketki,
Is possible that you run the script instead of kernel image then you have the virtual kernel partition overwrites only the kernel (zImage, zImage-dtb, Image.gz-dtb) by writing the new image.
But you need the Zimage you have to git clone https://source.codeaurora.org/external/imx/linux-imx and menuconfig and make your configuration and build.
You may ask to EDM1-iMX6 manufacturer if they changed the script.
Regards