Hi.
Just Google “Install Windows 10”. I installed single language since that was what it came with. But couldnt use the orginal 8.1 key after
ugrade to Windows 10. Then i just bought an new Windows 10 multi language and just typed in the key, and it fixed itself.
I download from Microsoft to a USB flash drive. All instructions easy to find. Dont need valid key to install, just click “later”.
You can use it without activation but wont get full functionality to change wallpapers etc.
After that almost all was working. Download drivers from this side(Tech Tablets), i used the old 8.1 drivers.
To sort out the remaining yellow triangles in device manager , install the drivers , point to the folder containing the drivers you have unzipped.
i didnt get write permission to Micro sd card in tablet before all yellow triangles in device manager was gone. Sorry for my English.