Cannot start hyper-v vm Turned Off.

Have istalled a windows update recently ?

Now , I did not. The only thing I was working with is the driver and Nport suite from Moxa that is creating the virtual com ports on my server. I have 15 of them. I noticed this morning that the application using the service I tried to restart did not received any serial comms from yesterday around 16:00. Then I went through the steps described. Gabe,

Have a backup of the Hyper v host ?

Nope, I do not. is still work in progress and I am working to finish the system. I have a snapshot from 10/11 I am looking to restore  that if I will be able to. I did export the vm and working now to import it on a different host ( the big problem is that is not a server just a humble Windows 10 machine with intel I5 and not sure if will be able to even open the vm that was set for 10 cores.

you can use the revert option like here:

http://techgenix.com/how-use-hyper-v-snapshot-revert-apply-delete-options/

Yeah, would be good if I be able to but the machine does not start  at all to be able to revert. I actually tried  unsuccessful. I still downloading the exported vm in to the windows 10 machine. Is crazy , the link is 10MB/s only and needs 1 hour and a half just for download ( and if does not work is wasted time ). Not sure if is any chance to use the vhd files associated with the state at 10/11, like directly restoring the snapshot. Not sure technically the idea is acceptable. Any thoughts? Thanks, Gabe

"Emulated Serial Controller" <-- Is there a serial pass-through device set but the device that was connected was removed?

No Philip, was not removed as the system is supposed to use all these ports. It is odd that after crash I was not able to bring up the machine. I did export the machine, the I deleted the VM and created a new one pointing the the vhdx disk from the crashed one. It started, I am not looking now to the serial connections just trying to restore the production server , then I will start digging again in the serial side. THe problem I have is that the Failover cluster the machine was part of is gone. I will take care later of that, I am focused to restore the service now. Do you think that is any chance to be able to restore the initial VM using the one I exported?  Thank you, Gabe

Could you fill in more details about the VM and host setup prior to choking please?

Something is not making sense here.

Remove the COM/Serial connections on the original VM on the original host. Does the VM boot?