I found this point before, there is only one of them in full service. I tried to restart the service on another one. when the second node in full service it will bring the first node down. I guess in HA, it may only have one active ccx engineer.
No, that's not how it works. Both nodes should be up and fully active; each one the assumes either 'master' or 'secondary' status. If you are new to this product you should spend some time reading the documentation to get familiarity with the basics before working with it.
If either node is not active, you cannot make configuration changes.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...