Can you please try if anything happens when you press Ctrl-Alt-F2? It normally should get you to the command line, which looks kind like:
If this appears, log in with your user, then run:
eos-diagnostics
Then attach a USB stick to your computer and run the following commands:
sudo mount /dev/sdb1 /mnt
cp eos-diagnostic*.txt /mnt
sudo umount /mnt
Remove the USB stick and upload the file which has been copied to the USB stick here in this thread (from another computer)