Serious Problem I need your guy's help ASAP

I have to fix a friends pc, when i got there I saw the weirdest thing. ok get this. The monitor turns on and it stays on perfectly no distortions for about 2-5 seconds them bammm! black like Samuel l Jackson , and i kid you not the power button doesn't change to standby yellowish orange, it stays green and if you turn the monitor back off and back on you get 2-5 more seconds then again then again and again, its hella annoying , dont have extra monitor w/ me, uhh and its not the backlight inverter did the flashlight test. do you know what it could be? Ridiculous I tell ya, if someone could help me out here it be much appreciated since im at their house now.

kielisgreg