Starting oracle rac node2 error: ORA-29701: unable to connect to Cluster Synchronization Service
ORA-29701: unable to connect to Cluster Synchronization Service

You need to make sure the the Grid Infrastructure services are started first. They provide all of the networking and ASM storage for the cluster, and you can't start a database instance without them.
On Linux, as root, run crsctl start crs
The command crsctl stat res -t should show you the state of all cluster services.