I searched a lot about this and ran through all the solution but non of them helped.
My laptop GPU is NVIDIA gt 540m so I tried to install
nvidia-legacy-390xx-driver throughout this tutorial by using the official nvidia.com package and again, ran into a "Black screen with blinking underscore" after booting.
By the way
Ctrl + Alt + F1 does work but didn't help...
OS: Debian 10