Hi:
Sometimes it can take up to 4 - 6 hours for the factory reset to finish, so give it some time.
If it stays there or fails, if the notebook was made in 2016 or later, it may be supported by the HP cloud recovery tool which you can use on another working Windows PC with W7 64 bit or newer on it to create a bootable USB recovery drive that would be equivalent to factory resetting the notebook, except that you boot from it instead of running it from the recovery manager program.
Here is an info link for how to use that utility...
https://support.hp.com/us-en/document/c06162205
You can see if your notebook is supported by the cloud recovery tool at the link below...
http://support.hp.cloud-recovery.s3-website-us-west-1.amazonaws.com/