Hi Bouya,
The factory default configuration usually pre-configure some of the ports that will be used later in chassis cluster (fxp0/control-link) and if one of these ports have configuration previous you form the chassis cluster, then you will have issues forming the cluster.
The fact that one node is in disable state means that the control-link is not fully coming up and this will also explain the CF alarm because the configuration is synchronized via the control-link.
I will advise to take the nodes back to standalone mode and use a "delete" at the configuration level to delete all existing config. Right after that set a root password and then commit the changes. After this go ahead and form the cluster again:
# delete
# set root-authentication plain-text-password
# commit
# run set chassis cluster cluster-id [#] node [#] reboot
Hope this helps you.