Angels have the Phone Box
Yeah, can't always believe the GWX program....
You could try upgrading again (and again and again?), and even if you do get it upgraded, you may find problems, which will only be resolved by a clean install. So, yes, your PC will work with Windows 10, but best with a clean install.
If you want to try upgrading again, be sure to:
Be in an administrative account, uninstall any 3rd-party antivirus, any monitoring software (like Speccy), disconnect any external drives (except the USB if you're installing from that).
You could also try recovering the laptop to factory condition and upgrading from that point, but you'd still have to uninstall AV.
Up to you (or your sister).