I'm a student and recently got a used PE 4600 from school

but the 4600 couldn't boot, when powered on it just sit there and the monitor is black (no signal input)

fan rpm goes max when powering on and some seconds after, rpm lower to normal speed 

no hard-disk activity

no beep

front lcd shows no error

led on back is blue (seem to be normal)

dust cleaned

already tried cleaning NVRAM, didn't help

PCI VGA card tried, didn't help

please help with that, thank you