Hello friends.
I have recently purchased my third Nokia N900 (used).
The previous owner sent it to me without resetting and there is something I cannot figure out how to fix.

The screen is set to lit (backlight time-out) for 10 seconds.
After that it goes to dim mode and remains dimmed for approximately 20 minutes.
After that the light switches off.

I do not know how he managed to make it stay dim for 20 minutes.
I cannot find any installed application for doing that.

How can I change that to e.g. 10 seconds?

Thank you.