Why is my computer screen randomly turning off for no reason?

Hello. I have a Dell latitude 5490, and it continues turning the screen off randomly. It stays plugged in almost 24/7 and I don't think it is a problem with the chargers. Usually when It happens, I am still able to hear the sounds from the website or application I was using, and it was fine, besides the screen. I also was once on a call with my friend, and the screen randomly turned off, but I could still hear him. It hasn't happened for a few days, but I do not want it to happen again and I want to figure out what the issue is with it. The last time it happened though, it turned off, I had to continue shutting it off using the power button to try and get it to work, and I heard the startup sound, but there was no display. I finally was able to get it into the windows settings that you can access while booting up, and the screen turned on, just the backlight was off,neo it took me several minutes to figure out what it was saying. The error hasn't occured since for my computer, but my brother and I have the same type of computers, and it has been happening even worse for him. Please help me.

Thank you,

Gilchrist Dean