Suspend-resume issue - Ubuntu 20.04
On a freshly installed Ubuntu 20.04 with the same problem, i.e. blank screen after resuming from suspend; on a different Asus GL502 laptop with GPU GeForce GTX 1060, I installed the Nvidia drivers with
sudo ubuntu-drivers autoinstall
(which replaced the Nouveau display driver from xserver-xorg-video-nouveau). Now it works perfect.