Windows 10 serial on OEM

Hello there,
after posting in my tables forums, maybe it's time to post here, as it seems that the problem is more Windows related.

So I have this Teclast X98 Air 3G tablet (Chinese brand) with Android Kitkat + Windows 8.1.
As Lollipop and Windows 10 were released, Teclast decided that new tablets would have those new 2 OS but they released ISOs for flashing the oldest tablet.
As it seemed that updating directly from Windows 8.1 to Windows 10 would made the system laggy, they suggested to make a clean Windows 10 install (after flashing Android).
Now my problem: I don't exactly know what version of Windows 8.1 was preinstalled on my tablet, but I suspect it was Windows 8.1 with bing (OEM).
I extracted the serial number, and keeped it in a safe place. Now I try to install Windows 10 but it says that the serial is not correct. I can complete the install process, but then my windows 10 is not activated.
So what to do? I have a genuine windows 8.1 (probably with bing) serial that cannot be used to activate Windows 10.

Thanks in advance!

Hi!
My friend also has a similar tablet, dual, android and windows.
But it's already win10, just not activated. I need to activate it online. Ok.

I bet u need to install back win8, upgrade to win 10 first before doing a clean install.
OR run gatherosstate.exe to generate a xml under win8. Use it for activation later after clean install of win10.

Older version of my friend's tablet also ran on win8.
Others may have better ways...

You can check your key with ShowKey to check what version it is.

As of the 1511 release of Windows 10 you should be able to activate directly using your key (for bing edition you would need to be running 10 Home not 10 Pro for the key to work I think).

Ok first of all thanks for answers.
Now please, let me understand better:

I bet u need to install back win8, upgrade to win 10 first before doing a clean install.
OR run gatherosstate.exe to generate a xml under win8. Use it for activation later after clean install of win10.

I don't know what's gatherosstate.exe and how to use it, but the main problem in this answer is that I can't reinstall Win8. When I try to reinstall it (using the serial) it says that the serial is not correct either, probably because that serial is valid for Windows 8.1 with bing and I can't find a Windows 8.1 with bing ISO (at least is not downloadable from Microsoft). So what to do?

As of the 1511 release of Windows 10 you should be able to activate directly using your key (for bing edition you would need to be running 10 Home not 10 Pro for the key to work I think).

Where to find this release? What's the version downloadable with MSFT MediaCreationTool?

Thansk again!

CapitanCatarro said:

Where to find this release? What's the version downloadable with MSFT MediaCreationTool?

Yes - Media Creation tool downloads an ISO containing Home and Pro and it will now give you the 1511 release.

If given the choice install home (if it picks up your key it will just install home anyway without asking you).

More details here Windows 10 ISO Download - Windows 10 Forums

Yes - Media Creation tool downloads an ISO containing Home and Pro and it will now give you the 1511 release.

Ok so I've already tried this method and it is not working, it says that the serial is not valid

CapitanCatarro said:

Ok so I've already tried this method and it is not working, it says that the serial is not valid

I'm a bit lost, sorry. What says the serial is invalid? Have you got 10 installed already and it is not activated? What version?

What does showkey say about your key when you check it?

If you are having problems getting the ISO from MCT you can try Tech Bench

Sorry for all the questions - I understand you can't re-install 8 but I'm not sure where you are exactly at the moment...

So I'll summarize steps made...

1. Saved serial number (taken with Belarc Advisory) from preinstalled (half chinese language) Windows 8.1 (don't know exactly the version, suspect Windows 8.1 with bing) on tablet
2. Formatted tablet
3. Tried to make a clean Windows 10 (HOME, HOME N and also PRO, everytime with the same result) install with ISO taken with MediaCreationTool, during install (and also after completing installation) it says that the saved serial is not valid
4. Tried to reinstall Windows 8.1 (ISO taken with MediaCreationTool again) HOME, it says that the serial is not valid

So i suspect that the saved serial, is from a WINDOWS 8.1 WITH BING OEM version and this kind of ISO is not accessible/downloadable anywhere (at least I can't find it, any suggestion?)

Still not tried SHOWKEY with that serial, I am in office now, and the serial is saved on a usb pen at home, will try this evening.

So I'm stucked but if everything is like I suspect, it's incredible. If I have a tablet/notebook/netbook with Windows 8 preinstalled, it seems that I can update to Windows 10 without problems, but if I want to make a clean Windows 10 install that serial is not valid...

OK, got it. Post the ShowKey when you can. Perhaps you'll need single language - it would be best to check it before downloading something else though.