Except partitioning, nothing else make sense of making it unbootable. I don't know how much Windows disk management effective in doing a good partition creation
I can only assume and speculate them that's all.
Back up all personal data & try clean installing once again & not going for partitioning.
Follow the tutorials given above, they'll help.
Nothing else really reason it out, hard drive came clean on testing, reseated everything firmly, changed BIOS boot order & other settings before install, so left is partition corruption.
But since, SFC scan came clean, that's also dim possibility, but it's worth a try to do reinstall.
Regards,