Dell Optiplex 990 Doesn't boot up Blue button 1/3

Ali_208

Prominent
Feb 26, 2017
2
0
510
I have a Dell Optiplex 990 it was fine a week ago I had no problem I didn't use it for a week now I have a problem when I boot the PC it power on and Fan is working but otherwise black screen USB doesn't work ( mouse and keyboard lights off) . Diagnostic Indicators the power button is Blue and I have 1 3 light up (no blinking), any help are appreciated