Hi-Grade VA250D - lights on but no post to ...

My VA250D when powered on has all the lights come on and stay on (power, wifi & 3 other lights), fan spins, but can't get the bios to post to screen or an external monitor. I can't use the power socket at the moment as it needs replacing, but the battery I'm testing it with is good (have used on another machine). I'm testing with no cd/rom or hdd installed. Memory seems to seat okay.
Any suggestions would be much appreciated :o) - there doesn't seem to be much help on this model on the internet ?!!
Many thanks x