mindray dc-n2 doesn't boot

At a mindray dc-n2 when i plug it in , it start up by itshelf.
Lights show up at the control panel ,but at the monitor it say "no signal" .
The 3 leds at the i/o are all on.
But from the 3 info leds at the control panel only the AC led is on.
What could be the problem..?