PowerEdge 2550 like zombie.

I have 2 PowerEdge 2550 (bought second handed) both stays in black screen, like no signal to the monitor, i mean, it has signal but, the color isn't even black, it's just the monitor's screen powered on. Besides, 6 seconds after turned it on, the amber/orange light starts blinking and the power supply's fan starts to fail... what's happening? what can i do?

P.S.: I figured out that if i disconnect the power3 cable, the power supply's fan doesn't fail, but the rest of the problem remains, only sometimes the blinking light stops.

Additional information: The previous owner said that one of servers works, and the other don't. He said that he powered on the server that works, and saw the dell's logo screen, and the the BIOS menu appeared for set it up, he didn't make the configuration and shut it down. So, later he went to take some pictures of the server running (for add it in the buy/sell site post's description), and it doesn't show anything, I bought both knowing the issues but, luckily for me, I discovered that both servers work, but has the problems that I described earlier.

Sorry if I wrote wrong, I'm spanish.