problem with AlphaStation 500/333

[Riccardo Veraldi]

Hello,
I have a AlphaStation 500/333.
today I boot it after a few months it was turned off. What happen is 
that nothing is diaplayed on the monitor.
keyboard is plugged and working. I changed video card I Also swapped the 
video card in al lthe PCI sockets, nothing happens...
I notice that when I Boot it, the scsi disk does not start all the 
times. Sometimes it receives signal to start from scsi bus and sometimes 
it does not. I changed disk as well, same behaviour.
Another strange thing is that the twisted pair on board card ahs both 
the 2 green led turned on.
I Am thinkign something bad happened, it looks like damaged...
anyone has some hints which could be useful for me to identify the problem?

thank you

Rick