I would move through this list and make sure you've double checked configurations:
- Storage Failure - Check your storage, make sure it is configured and spun up correctly. Is storage readable by your Hyper-V instance?
- Is there enough memory allocated for the VM to start up. Are the other VM's essentially taking up all the RAM and storage.
- Incorrect network configuration - Is it contained in the correct VNET or does it have any NSGs/Policies that are blocking it from starting it up.
It might help to reinstall the HyperV role, I understand you've mentioned that it won't be reconfigured/reinstalled but in a lot of scenarios this actually fixes the error, this link will take you through the installation guide in case you need it: https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/get-started/install-the-hyper-v-role-on-windows-server
Although you are not receiving an access denied error, it might be that there is something setup in the VM that shouldn't be but the error message you are receiving is a result of that. check this guide from Microsoft: https://learn.microsoft.com/en-us/troubleshoot/windows-server/virtualization/hyper-v-virtual-machine-not-start-0x80070005
Again, double/triple check the policies, roles, and NSGs to rule out any explicit deny errors. Also check if you have spun it up in a different location to the rest of the VM's sometimes this can happen by mistake especially if you are deploying VMs manually outside of Terraform/ARM.