1 make sure tv or monitor is on and change source to proper input IE Hdmi 1 or 2 etc. 2 Ensure your ps3 is off but ready to be turned on. Fat ps3 has switch in back that need to be in on position. 3 hold power button for 5 to 6 seconds and let go after 2nd beep, it should come on with a beep and wait for 2nd beep. 4 this should reset your video, if display flickers then it should come up. 5 if it doesn't, try turning the power off then on again. Repeat steps 2 to 4 if it doesn't work. If you keep trying and it doesn't work, then your unit might have to be repaired.
Just so you know, Sony will not accept refurbish units for repair. They will send your unit back to you if it was not refurbed by them or an authorized dealer. My 60 gig had YLOD and Sony sent it back because GameStop refurbed it first. I'm having a similar issue with my 80gig now. I got replacement ps3 slims so my 40g, 60g and 80g are just collecting dust.