Brightness issues
It comes from here: https://trisquel.info/es/forum/plymouth-corruption
The point is that cannot be adjusted brightness without doing a trick: pulling out firstly the power wire.
The laptop used is this one (trisquel 5.0):
http://www.h-node.com/notebooks/view/en/30/SA50-110/2/1/TOSHIBA/undef/undef/undef/undef/undef/undef
I'm having also problems with other laptop (trisquel 4.5). The problem is a bit different: The information of the corner says that brightness is changing, but it is not happening really.
This is the computer:
http://www.h-node.com/notebooks/view/en/254/ASPIRE-5736Z-454G32Mnkk
At any case, the set of brightness is done with Fn-key.
With some video cards it is possible to set brightness via a file named brightness below /sys in some subdirectory.
It contains a number 0-100.
Daniel, could you do some tests and report here?
Do
sudo showkey
to see what keypresses are being generated when you press Fn+Brightness.
Do that for the first laptop both before and after pulling out the power. In other words, both when the buttons are doing nothing and when they work.
I don't yet have an idea of where to look for the second laptop's problem.
At any case, the result is always the same:
keycode 225 press
keycode 225 release
or
keycode 224 press
keycode 224 release
depending if your are lowing or increasing the brightness.