where did you buy your a4000 from ?
I don't want to ruin your party, but if you think a second hand machine that's 15 years old will work out of the box right away you're too optimistic. there are some common failure points with a4000, leaked/leaking battery, leaking smd caps, broken ram clips. If you can't get your a4000 working when you get it, let us know what's wrong with it.