How much space do you have to install things to ( DF ) lowercase in a terminal should show that ......
.... and if you try to update and add LXDE - can you get a graphical user interface ...... lightdm is the login manager
which will make it simple to choose a desktop environment to work from .........
The first thing I do is when messing with different systems is to have a light desktop to fall back to
sudo apt-get update
sudo apt-get install aptitude
sudo aptitude update
sudo aptitude install lxde
sudo aptitude install lightdm
also the light ones tend to work best when everything else stops. ( the others I use are E17 and awesome )
But LXDE should give you a easy start point to work from with a gui - that will make things easier to report back
what is happening .........