When I click on the "Upgrade to Windows 10" icon on my taskbar, it opens but closes itself right after.

[Kinderpunch]

Sorry about my system language.

I recorded a video of what happens : https://youtu.be/C8_2x5Vy_P8

 

[N3rdR4ge]

if you dont want windows 10 disable gwx.exe from your startup programs.

if you do want windows 10 you can just get it here. download the correct tool and follow the steps for the upgrade.
https://www.microsoft.com/en-us/software-download/windows10