Hi me again, my daughters laptop still wont boot up at all ,tried swapping known good identical memory cards, hard drives and optical drives from other Inspiron , also tried disconnecting battery connector   under the keyboard and running direct from mains,still nothing happens except lights flash next to on off switch, and fan runs for a couple of seconds.

However what I have noticed is if I the put battery back on and try to boot up with battery alone the computer tries to boot up with lights flashing at side of on/ off switch and fan runs but then shuts straight off again until I push on /off switch again.

 But If I connect up to the mains adapter the computer will continually try to boot up and shut off also with fan running  until I pull the mains adaptor back out,but regardless of what I do the screen remains blank and pressing the F keys achieves nothing at all

Thanks for your thoughts and comments