Question : Problem: will not boot up properly with both battery and mains connected?

will not boot up properly when plugged in off mains with battery inside, the lights go on but nothing on the screen. it powers on fine when the battery in taken out.  it also power on fine with the battery in and mains disconnected.

I tried a trust universal power adapter to see if the 'liteon' fujitsu supplied psu was the problem, but the exact same thing was happening - ie booting up fine without battery attached but when both battery and mains connected - power light on and battery charging light orange but nothing on screen?  Could it be a faulty battery?

Answer : Problem: will not boot up properly with both battery and mains connected?

The problem is either the battery as posted earlier or the motherboard power controller is faulty.
What does your manual say about the flashing orange LED as this may be an indicator for troubleshooting.