What I would try is
Go to the manufacturers website, look up the computer by the model number, download and install the video drivers, restart the computer.
If that does not fix it, I have very little doubt that it could be a bad monitor, as you said.
But from the description, column of dots, that's pretty much what I see when a system has lost the video drivers, the system defaults to the lowest resolution, and everything looks big, like it is made out of dots.