update: turns out that I both have zero patience and the hard drive was actually completely dead which is why it wouldn’t boot. Upgraded it from a 5400rpm 500GB HDD to a 7200rpm 1TB HDD (I don’t have any SATA ssds) and it is now running High Sierra. It’s very slow obviously so I’m trying to either install Windows/Linux or downgrade it to macOS Sierra or El Capitan.