I will recommend you to do the following before changing the linker file
if the .elf works and you can download and debug I suggest to get the binary from the .elf file (elf and binary may be created with different settings i.e. compiler or linker flags may be different, epecially if you imported the project ), so to get the binary you can do it executing this command :
arm-none-eabi-objcopy -O binary add.elf add.bin
I am sure that that method shuld work because rememeber that the .elf file is the binary file + debug infomation and meta data, so you sould be able to extract only the binary data from a file that you already know that is working.
also you might want to take a look at this post: