I am using this display with my Pis. Thanks to a tutorial they put some time ago, I have been able to control the brightness on the screen. Recently, I was testing some nodes on the Pi using a continuity tester and while there is no apparent damage to the Pi or any change in its behavior, suddenly the brightness control for the Waveshare 7in is not working.
I tried another one of the displays I have around and brigthtness control does not respond on it either. I tried both displays with a different Pi with no results. Then I tried doing these using a different GPIO pin and have still come up with nothing.
Because of this, I am unable to diagnose the source of the problem.
Is it possible the the displays are now somehow damaged?