Hi,
Connect an external monitor to the laptop and check what its' display is like.
If there is no line showing on it then it is most probably a hardware problem with the laptop and your installation activity could have been just a coincidence.
If the external monitor also shows a line, try starting the laptop in “safe mode” and check if the line appears.
If it does then again it could be a hardware problem.
If there is no line when in safe mode then it is most likely a driver problem.