I finally managed to find a solution that worked for me (at least for now):
- Download Display Driver Uninstaller and the latest NVIDIA Drivers for my card. The OEM drivers will not work!!
- Reboot into Safe Mode and uninstall the PhysX Engine and the GeForce Experience.
- Reflash BIOS to known working version. (Thank you NVIDIA Forums!)
- Boot into regular mode and install the NVIDIA drivers and all the related software.
Apparently ASUS laptops have an issue where BIOS updates and Windows 10 can sometimes cause Code 43s to appear.
In my specific case, I even had to go back to BIOS version 214 for the Asus Q550LF. The flash utility would not accept an older BIOS, so I had to force it with winflash /nodate bios.214
(src).