HP Elitebook 850 G3 notebook display very dark, no backlight

Question

I have a problem that is similar to the one described a long time ago in this question: My HP Elitebook 850 G3 suddenly (from one day to the next) doesn't seem to show anything on its display. Only a bit later I found out that it does indeed show the display contents, but that the backlight wasn't working.

Strangely enough, when pressing the fn-key and then simultaneously the break-key (which happens to be the right shift-key in combination with the fn-key, the backlight is turned on and stays on, as long as the break-key is being pressed (the fn-key can be released).

When the break-key is released, the backlight turns itself off. Completely.

Some more things to note:

• The longer the break-key is pressed, the longer it takes for the backlight to turn itself off when the break-key is eventually released - almost 1:1 in terms of duration.
• This is not Windows related, as the same behaviour is present within the BIOS setup
• Loading the factory defaults in the BIOS setup didn't change anything

Answer 1

To narrow things down, I started to install the HP Assistant software, as my plan was to install everything it suggested to download/update. First item from the (long...) list was a BIOS update (the current version was from November 2020 if I remember correctly).

After installing the update and rebooting the system, the behaviour described in my question was gone - everything back to normal and the backlight works as expected.