With all respect, but your instructions are slightly misleading.
DCIM is NOT a root directory, it is a directory (= folder) that is located in the root directory. Therefore you have to copy the firmware file into the root directory (to the same place as the DCIM directory). If you copy the FW file into DCIM directory, D700 will not recognize the software.
It is possible that you had issues because you copied the file into the DCIM directory.