Question Monitor doesn't display video and stays black

Sep 9, 2019

I have had some problems with my monitor (Asus ML239H). At first, it used to flicker and then go black (not standby just black screen). I tried having it fixed. They changed some parts and told me that it is fixed now. But then again it started doing that again. I had it sent to another repair shop so maybe they have better luck, but they just said maybe the adapter is not working. I bought another adapter, it went black again.

The issue:
  1. The screen flickers and goes black
  2. In the past, when this happened, resetting it in some way would have the screen back on; that is, turning on and off, switching the input, or unplugging and plugging one of the power or HDMI cables. (Repeat)
  3. When I connect the monitor to my laptop it still persists. But the repair shops told me that it is fixed and it had no issue.
  4. After changing the adapter, I haven't experienced the flickering and just goes black.
  5. When it goes black, however, turning it back on is the challenge. The only way I have found which works is to unplug the HDMI cable and turn it on and off a few times; otherwise, it would just display for a moment and then goes black again with the HDMI plugged in.
What I have tried so far:
  1. Change the cables (i.e. HDMI, VGA, DVI, Power cord, and Adapter)
  2. Remove the display drivers (Asus GTX 750ti) multiple times and updating it manually, automatically, or via the windows update.
  3. Using my laptop as another system to test it.
  4. Having it repaired
  1. I am considering buying a new display, but I want to be sure that the problem is the monitor and not something else.
  2. I don't have problems playing any video game, but is it possible that the VGA is causing the problem?
  3. Last but not least, when I turn off my PC, some devices stay on. For example, my mouse and keyboard's lights and the lights inside the case. Is it normal? Does it have anything with the display?
Thank you for your time.
I tried to explain everything thoroughly, but I will answer any questions you guys might have.

P.S. There is no integrated graphics on the motherboard, so just one display output.