"Could'nt update to Windows 8.1. Sorry, we couldn't complete the update to Windows 8.1 We've restored your previous version of Windows to this PC. ERROR CODE: 0x80070002 - 0x20009."This is most likely because the HDD on which Windows has been installed in not the one you booted on.
In this case, change the options in the BIOS in order to boot on the Windows HDD, upgrade, then restore as before.
