In http://psref.lenovo.com/Product/Lenovo_Laptops/ideapad_520S_14 I see it comes with Windows 10 Home 64 bit. Why did you install that yourself? Are you sure it was new?
Anyway, after 5 days it should still be in warranty, so better return it.
I have issue with new 520S-14IKB. I bought it 5 days ago.
Installed Windows 10 and updated to latest version. Installed all drivers from Lenovo support site.
Laptop freezes randomly few times a day. I can't get patternt, because it sometimes crashes while watch youtube, sometimes when swithcing windows, sometimes just by using some text editor.
It just stucks, I can't click anywhere, cant switch windows with alt+tab, can't open task manager. I can move mouse and that is it.
No any message, no "not responding" message.
When I put it on sleep by pressing power button, and turn it on again it runs normally, as nothing happened.
It is becoming really annoying because I can't find out what causes the problem.
I tried everything I could find on web, also installing intel graphic driver from Intel site manually, turning off Link state power management for PCI express which I found on internet as solutions for windows 10 crashing.
I am getting really desperate about this and thinking about returning laptop to my seller back.
Can anybody help please?
Thanks in advance.
Kind regards

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic