Upgrades usually involve two processes... update and activate.
Update will modify your "startup version" and activate will trigger the reboot necessary to use the startup version.
You can update all components with a startup version at once but the activate step has to be taken in an specific order as there are internal dependencies that rely on each other to work as they should.
Follow the guides to see what needs to be upgraded first, based on the version you are upgrading from/to.
The FIs do not get sync up with each other even when they are in cluster mode. To activate the new firmware on the FIs, you need to reboot them; the idea of having dual FIs is to have redundancy and that allows you to have at least once path up while the other FI is being activated.
You dont need to run any commands to verify the upgrade is successful as you can see all that from the GUI, but you can check your paths are up and your "HA" is ready with the following commands:
#show service-profile circuit
#show cluster extended
HTH,
-Kenny
