From SSH as root to AHV can you run

virsh list --all 

This will show you the power state of all VMs on the host. You can then use virsh start against the required CVM. There may be a bigger problem here though as CVM tends to boot on start up of the host so you may need to look in the serial console of the CVM but we'll come to that once we know if your CVM is able to power on.