So, I botched the environmental variable PATH and my HP Envy dv6 no-longer boots Windows 8.1 Pro 64bit. After no luck with booting from a flash drive, I plan on offloading the entirety of the drive onto an external HDD, via a pretty old Dell Dimension 5150 (Windows 7 32bit). At this point, I've removed the laptop's HDD (ST750LM022) to find it uses a Wistron CLS 17 Main HDD cable. It also has an unconnected 4 pin port labled A120621.
I intend to offload the entire drive, wipe it, reinstall Window 8.1, then transfer my files back onto it.
Is this plan viable? Is there a better approach? What do I need to do from here?