Y7000 Screen flicker...ideas?

I just got my Y7000P-1600 (model 81LF, i7-8750H, 144Hz panel) back from Lenovo for a screen flicker repair issue. Turns out after almost two weeks away that it was diagnosed as a software issue and the SSD was simply reimaged.

After receiving it back, I took the windows updates and the driver updates from Lenovo Vantage and the flicker came back. Example here: https://photos.app.goo.gl/X9QQM5V76tcipTWt5 . I've also see in games that the screen will completely stop updating until I alt-tab out and alt-tab back in. Since this has Nvidia Optimus, it seems like that might indicate its related to the embedded Intel graphics?

I use the restore partition to revert back to the clean windows install and the flicker did, indeed, seem to disappear again. Thinking it would somehow be either Intel graphics or Nvidia driver related I was careful not to upgrade those drivers and everything seemed ok.

I then upgraded to Windows 1903 and the flicker is back again, though no graphic drivers were updated as part of the 1903 update, so it seems it's not graphic-driver related.

Any suggestions? I've been searching for Y520/Y7000 issues and not finding anything...

 

Update:

I was finally able to reproduce the problem not only on windows fresh install but also the BIOS screen. Motherboard and screen replaced.