Dell monitor comes on for a second then goes black

I have looked & looked to no real avail to my problem. A friend of mine that lives 2000 miles aways said her monitor just went blck one day she said that it comes on for a second then just goes blank? I tried to talk he through starting in safe mode but she said it does the same thing before she gets a chance to get to safe mode. It’s not the monitor because she tried a differnt one & it does same thing? Any advice?