Acer Aspire 5610 boot issue

issue booting up notebook. have acer aspire 5610. 
turn on, and starts boot process, goes through motions and passes the 'f2 setup' stage and as soon as it does that, everything just seems to die, there is nothing showing on screen although the screen is 'on' as there is some illumination of screen. just no graphics etc...  no noise coming from unit either. fans started on startup but died as well when got past the 'f2' stage.
have tried:
removing battery and rebooting with a/c power only. - no effect checking for fan blockage etc.. all is very very clean. removed and reseat memory checked processor but doesn't appear to be incorrectly seated.
tearing hair out with this, any suggestions??
Regards Chris