Mint 18 power manager fault?
 

Good day, I have Mint 18 MATE running on a Dell Inspiron Zino, which is over 5 years old, but Mint after idling for hours does not go to sleep. I adjusted power management and in Actions it is set to 30 minutes and Display to 10 minutes, but after these times even with the boxes checked Mint is not sleeping. Is there a fix?

do you mean the screen doesn't even go blank?
please elaborate.

Yes, the screen does not go blank. It simply remains on.

try to enter this command in a terminal:
(without touching the mouse of course)

does it go off then?

The screen remains on unless manually turned off from control panel, menu and quit. It should timer off but that it does not is the problem.

ok, so if "xset dpms force off" doesn't even make it flicker, then imho you're looking at a deeper problem. meaning, not related to desktop environment and such, but rather to the kernel.

search compinations of keywords:
- linux
- laptop (?) model
- acpi

what kernel version? if you're unable to search, you could just try a newer kernel.

It's ok, I set the timers again so the screensaver comes on before the go to sleep option, restarted and now it works.

Normally Linux does not a restart.