Sometimes, the VM will fail to initialize if there is no enough memory can be assigned for the VM boot.
Please ensure that there is enough memory could be assigned for the VM.
If you suspect the issue is related to the Windows updates, please try to remove the updates or install latest Windows update to see if the issue could be resolved or not.
Also, I did more research and found below two treads which mentioned the same problem as yours. Please kindly check if the solutions are helpful for you.
Hyper-V machines not starting after Windows Updates Server 2012R2
An error occurred while attempting to start the selected virtual machine(s)
If the Answer is helpful, please click "Accept Answer" and upvote it. Thanks.