I'm not sure if the MX480 upgrade to the junos is the same as an MX240?
I am just completing an MX240 upgrade from 16 to 17 on a dual routing-engine device. After a few problems it is now upgraded.
To ensure "master switch" completed successfully I also implimented GRES.
I loaded the software to /var/tmp and just completed:
request system software add re1 /var/tmp/(Junos file) no-validate
request system software add /var/tmp/(junos file) no-validate
Make sure you are on re0 (You probably will be), then run:
request system reboot other-routing-engine ---- You won't lose connectivity with this command (or you can just reboot the device but that defeats the purpose of redundancy)......
Then you either need to switch master (you will need to if you want redundancy, but this then gives another problem of BGP reconvergence which can take a few minutes). Use this command:
request chassis routing-engine master switch ---- Cause BGP convergence
or, logon to re1 and then complete the same command as above by rebooting the other re.