Due to changes in systemd (bug?) if you have a Penguin T4 revision A (ie TPE-PENT4LAPA) there is a slight adjustment to the T4 documentation needed to get suspend and the LCD backlight working properly. This applies if you enable suspend and the LCD backlight isn't working as expected.
acpi_backlight=native is a kernel parameter to resolve the issue with the save state of the backlight where if it is beyond 75% when the system is booted you get a blank screen. It's possible to use the FN key in combination with the F8 and F9 keys to adjust the brightness and temporarily resolve the issue, but the proper fix is to edit the grub configuration file and add the acpi_backlight=native kernel parameter.
Suspend not working?
1. After installation open a terminal window and gain admin access (click activities or your menu and search for / go to terminal):
Once at the terminal and (or in the chroot environment enter the following command):
nano /etc/default/grub
3. Find the line that reads ‘GRUB_CMDLINE_LINUX_DEFAULT‘ and append ‘ acpi_osi=! acpi_osi=Linux acpi_backlight=native’ to the end (without the quotes)
Save it, to save the file: CTRL+X, Y, ENTER
4. Now, update your grub file and reboot.
update-grub
reboot