Alright guys, I'm back and..
So far so good!
I've been testing it for some days and Manjaro KDE seems to be working just fine on the laptop.
What I did is this:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pci=nomsi pci=noaer"
And this:
or Use the GUI option available nowadays, if you so desire.
I changed the Nvidia driver using the Manjaro GUI from 510 to 470.103.01 Prime (I did not go for 495 because it was not in the list and I said it would be better to stay away from terminal for now #lol) (also I did not want to go for Bumblebee version, I've heard that's old)
This laptop is mainly used by older member of the family in a very conservative fashion.
It is only being used for and has been so far tested with Chrome, web surfing, e-mail, facebook and Onlyoffice. Also HD movies in 1080p from hard disk are running very well and Nvidia does not go past 40-42 Celsius degrees.
Also watching movies via HMDI works fine.
No more errors when shutting it down, no freezing, it stays pretty cool all the time - Nvidia temperature with Thermal Monitor shows it stays between 37-42 Celsius degrees which I think is just fine.
So I think that the MSI grub thing was the issues.
I am glad it works but can someone still explain to me what that means? #LOL

(I cheked the internet but I don't think I've been looking for the right thing.)
Overall, it works! Thanks
