Windows 10 won't activate?

[jdaniel 125]

hello

don't mind my terrible grammar, I'm quickly typing on a phone.

so, I have a custom made PC with no OS that my uncle gave me. since it had no OS, I figured i would deactivate Windows 8.1 on my old eMachines to use the product key on my new custom built. anyways, I used an elevated command prompt to deactivate the key on there. after that I formatted the hard drive to revert the eMachines back to Windows XP. now that I had a working product key. I installed Windows 10 via a USB created with the media creation tool. but for some reason. Windows tells me that the key is being had on another PC even though I deactivated the key... I text chatted with Microsoft support and had a guy remotely control my computer to try and fix it for the rest of the night, But now whenever i enter the product key it says "Windows cannot activate with this product key." can anyone help? The support guy doesn't know what's going on either

 

[USAFRet]

That 'deactivation' actually does nothing. It simply tells that particular PC is has no OS license. It does NOT call home and tell the activation servers.

So, that 8.1 was an OEM license? If so, the activation of Win 10 WILL fail.
You need a new license for your new system.

 

[jdaniel 125]

the OS key is a retail license, I got it from a retail copy of Windows 8.1

 

[USAFRet]

the OS key is a retail license, I got it from a retail copy of Windows 8.1

Then you need to call MS. They are the only ones that can fix this.