Dell all in one with no monitor

[Rainmaker29]

I bought my mother a dell all in one a little over a year ago. Last night she calls me and says the screen went black. I stopped over today and the CPU seems to boot up but just a black screen. The screen does get lighter at start but goes black after about a minute.
Since I have no monitor it is difficult to run any diagnostics. Any ideas?

 

[Rainmaker29]

Check http://www.dell.com/support/article/us/en/19/SLN289659/EN for troubleshooting Dell monitors.

I did all of that first. I cannot get the Bist test to run. It has power, the light is green. I am going to try and bring it up on her flat screen tomorrow, and see if I can get it to go.