I have a Dell 15 l502x with NVIDIA GeForce GT525M with Optimus in it. I installed a fresh Ubuntu 16.04 LTS on it but am unable to use the NVIDIA card. 2 observations: 1. All NVIDIA drivers installation fail, I have tried many versions. I saw this error: W: Possible missing firmware for module i915. It gets stuck in the login screen loop after reboot. 2. Settings show that the graphics card is 'Gallium 0.4 on llvmpipe (LLVM 4.0, 256 bits)'. When I do 'sudo apt-get install xserver-xorg-video-intel' , it throws this error: the following packages have unmet dependencies: xserver-xorg-video-intel : Depends: xorg-video-abi-20 Depends: xserver-xorg-core (>= 2:184.108.40.2062) E: Unable to correct problems, you have held broken packages.
Background: I had Ubuntu 14.04 LTS before this where I tried installing ROS. I do remember it saying something like, some packages could destroy my Xserver. But, I installed Ubuntu 16.04 over 14.04 as fresh install, without updating. I apologize, I am a little new.