Aurora R4 desktop not starting

I have a 3 year old R4 that's worked great till a few days ago, was online gaming w/o problem, stepped away for about 30mins and came back to find the desktop off, well starting up: pwr light goes on, fan starts and then turns dark, 2-3 seconds and it does it again, and again... nothing on my screen no boot screen or anything. Unplugged it and went out, came back a few hours later and plugged it in and it was fine... tonight same thing, now leaving unplugged and searching for a solution....

So far I have: 

-Dusted and vac'd out the entire case, dusty but not disgusting. ( i do this on 6 month schedule already)

-Checked the power supply, green light steady and fans running when pushed.

-Did the "complete power dump" by holding the power button down for 2 mins with it unplugged. (Not sure why to do this but I did with no help).

Can't get it to power on long enough to see anything on the screen so I can't get to safety mode.....

Any ideas will be appreciated.

Thanks