Windows 8 Issues Activating Windows 8.1 After Motherboard Replacement

Hi everyone,

I find myself in a bit of a bind.

I'm fixing a PC for a family friend - the motherboard died. Anyway, it was running Windows 8.1 - (I believe it was a cracked version - dunno, didn't build it).

So anyway, the motherboard died, so I swapped like for like - A Gigabyte SKT-AM3 78LMT-USB3, which I believe is a non UEFI board.

So all is fine, I downloaded the media build tool, used a USB stick to install windows 8.1 - standard 64-bit edition and Windows is up and running and updated.

So I wanted to buy a legit key for it to activate it. However, when I try, I get a message saying (paraphrasing): you can't currently buy a key online, try again later or buy a retail copy.

Would I be right in saying that Microsoft have dropped the activation servers for 8.1 or is there another issue?

Any advice would be welcome.