Just thought I would share a working method to update the Nortek HUSBZB-1 device, at least the Z-Wave side. This device is both a Zigbee and Z-Wave, and doing this upgrades the 2014-2015 based firmware to one updated in 2020. As I understand this is the last update for this Z-Wave chip, as the 500 series of devices has been replaced by newer 700 series devices.
Now, there isn’t really a strong reason to do this update, but it does include many years of fixes, and add SmartStart and S2 encryption as well as APIs for NVM backup and restore.
Just thought would share, the real credit goes to jp0550 how posted this in the Hubitat forums (seems Hubitat ships HUSBZB-1 sticks for some deployments).
It isn’t really easy as you do need to open up the stick and short a pin during the instructions, so damage to you device can occur. I can confirm it works though, and now my device which previous reported as Z-Wave 4.05 now shows as Z-Wave 6.09.
On a side note, I updated the Zigbee side using this docker container. It does need to be done on a windows machine. It upgraded the Zigbee stack from 5.4 to 6.6.