It seems that my Lenovo laptop is not totally compatible with Linux. Let me explain:
Five months ago I bought a Lenovo ThinkPad T490 (i7-8565U, NVIDIA GeForce MX250 (and, of course, the Intel UHD 620), 24 GB RAM, 1TB SSD) without OS as I had planned to install Linux on it. Because I like Mint with KDE I decided to install the latest version of that, I believe it was Mint 18.3, as KDE is not supported any more on later versions. I had been using that OS and desktop environment on my previous laptop (also a ThinkPad but model T440s) for quite some time with no problems at all. Therefore I was surprised to see that I could not install it. The live stick worked, but the installation process was interrupted somewhere at the end, where the installer said that GRUB was missing or corrupted (or something similar). After trying to install other KDE OSes, i.e. Kubuntu and Neon, without success, I managed to install the newest Mint 19.2 Mate.
This worked, but barely. The screen flickers a lot and only stops when I switch the graphics driver from Intel to nvidia or the opposite. Also the fan is ON almost permanently, without heavy graphical work, not even a film. Some icons and bars are also not integrated very well or shifted.
Now, when I wanted to install a new OS, not even that would work any more. It was not even possible to properly boot into the live OS from the USB stick (I tried Kubuntu, Ubuntu, Mint KDE, Neon, Debian and Fedora with and without KDE). The boot process always froze, sometimes just when the home screen was showing. The only working live OS was the one, that I had used to install my current system (Mint Mate). I also created live sticks with LiLi on Windows, however, nothing changed.
I have heard of processor problems on this model with Linux, however, I cannot say that I have experienced that. I have been thinking about installing Windows on it an resell it, but I am also not sure that this is going to work.
Google could not help me until now. It seems that I am the only one with this problem... which is not very reassuring. My preferred solution would be to setup a fresh and well working installation with my favourite Linux. But I am open to alternatives.
Has anyone an idea how to solve this problem?
I'd be glad for any help.
EDIT: Lenovo support assumes it's a hardware problem. So, it's not really solved but it's Lenovo's turn now to try and fix the problem.