Hi I don't know if this will help but I had a similar issue. I have an MSI GS66 and I'm duel booting pop and windows. One day I was trying something and switched my graphics on pop to discrete and when I changed it back to integrated I just got a blank screen on boot up. So I went to windows to see if I brick my PC somehow but it worked fine and would switch cards fine. I was able to boot into pop with the discrete card but when I changed it to mshybrid in windows just a grey screen. How I fixed it was go into the bios changed the graphics from discrete to mshybrid then will it was booting hit the spacebar a bunch and I think it brings up systemmd. Anyway it gave me three options first was to continue in current kernal the second was to boot into older kernal and third was firmware. I picked the older kernal and it booted just fine all my apps and stuff were loaded and working. Hope this helps.
