How to stop laptop from going to sleep when lid closed (18.04 LTS Mate)

[Colin Law]

As a matter of possible interest, I had the opposite problem, that it
would not suspend on closing the lid, because I have a second display
connected and the powers that be seem to have decided that if I have a
second display connected then I don't want to suspend when I close the
lid.  I tried a number of possible solutions for this, I don't want to
have to mess about finding the suspend option with the mouse, that
takes much too long.  The solution I found was to link a keyboard
shortcut (Ctrl+Alt+U) to the command
gnome-terminal -e /home/me/bin/suspend.sh
where the file contains
#!/bin/sh
systemctl suspend -i

and that works well.  I don't remember why I couldn't just call
systemctl from the shortcut.  So, having prevented it from suspending
when you close the lid, and if the BIOS update I think you are
attempting in another thread fixes the inability to resume problem,
this might be of use to you.

Colin