Run this endpoint, once it says it worked then try running it again and make sure it took. Then do a shut down and unplug for 30 seconds, reboot and try the firmware update again.
yourHubIP*/hub/advanced/installZipgateway715
If I am reading that correctly I think your gateway is on 7.11 (unless that is the firmware, I always forget which is which in that list) so possibly updating it to 7.15 will allow it to work.
If you get the firmware updated you will then want to update the gateway to 718
Full instructions here: Updating Z-Wave radio on C-7 hubs after version 2.3.8.122
