Hey guys had similar symptoms (although mine is a Gen 6 Carbon), occured right after a windows update. Very annoying because clearly the whole system is working. You can get to the BIOS screen and it all works fine, and also same behaviour where you can plug in an external monitor and run it as usual, but the laptop screen stops working after bios/soon as you get to the login screen. My solution was to do the ‘driver uninstall’ for the screen from device manager, then reboot into safe mode, this seems to have reinstalled the drivers and now all works again. Edit: so 5 housr later, had more issues again with drivers uninstall not actually uninstalling - use this tool for a more comprehensive uninstall, https://www.guru3d.com/files-details/display-driver-uninstaller-download.html Then go to the lenovo official site and download older but more stable graphics drivers. Hope this helps.