Laptop screen is black after restart
Solution 1:
It's a longshot, but maybe the screen is in sleep mode and doesn't turn back on after a restart. This is a note I wrote to myself for when I do formats: "remove the screen locker light-locker on laptop and replace it with xscreensaver; xfce4 power manager doesn't restore screen power so disable 'Display power manager' in its settings"*. So in your power manager, disable its display management so it doesn't go to sleep, or blank, or switch off.
*It's a known bug: https://wiki.ubuntu.com/TrustyTahr/ReleaseNotes/Xubuntu
PS Haven't the reputation to comment.