After updating Windows 2012 Server, VM only boots into a black screen or recovery mode. Running a chkdsk on C:, shows no errors on the file system.
Windows 2012 Virtual Machines
This can happen when the update doesn't complete. Usually getting the VM to boot into safe mode will cause it to revert the changes made from the update, and then it will boot okay.
Getting the VM to boot into safemode can be tricky, here is one method:
Open the console to the VM, then shutdown the VM from the UI, leaving the console open so you can access it quickly once the VM is started back up.
Start the VM from the UI then switch to the console window and highlight the url and hit enter twice, basically refreshing the console connection. Continue to do this until the connection is successful.
If the windows loading screen is showing already, then hit the "Send Ctrl+Alt+Delete" button in the console to restart the VM.
Once it restarts, hit F8 multiple times to get into the boot options and then select one of the Safe Mode options.
The VM should then start to boot into safemode, and detect that the update had failed. It will then start reverting the changes. Please wait. It may reboot a few times on it's own, and continue reverting changes.
After it finishes, the VM should boot normally on its own.