This is a Toshiba laptop that came in dead, no lights, nothing. I've changed the DC jack, pulled every card and plug but still nothing. The power lights in the front don't acknowledge that it's plugged in and battery-in or battery-out has no effect. I see no signs of water damage and the user claims that it has not had any. I'm just wondering if anyone has any thoughts on how a board comes to be this dead.
You did not give a specific model number, so some of these points may or may not be valid for you. Pardon the order, as I wrote them as I thought of them. Most of these possibilities can be ruled out with some simple voltage checks on the motherboard.
Some Toshiba laptops run on 15v rather than the much more common 18v-20v.
On the DC jacks, some Toshiba laptops use a 3.0mm center pin and some use a 2.5mm pin (this can happen in an otherwise identical jack)...depending on which combination of DC jack and DC plug on your AC adapter you have, this is a potential open circuit.
Some newer replacement jacks have a recessed center pin to make them less susceptible to damage. This is more common on Gateways, but some Toshiba's use the same series of jacks. The DC plug on some AC adapters also have recessed contacts for the center pin...depending on which combination of DC jack and DC plug on your AC adapter you have, this is a potential open circuit.
Some models of Toshiba laptops have an SMT fuse near the power input of the motherboard...another potential open circuit.
Have you verified that the laptop is not internally shorted and shutting down your AC adapter?
"the video problem" is not likely to cause a "no signs of life" situation...unless somebody who shouldn't have, has already attempted one of the many homegrown reflow processes and shorted the motherboard.
Some Toshiba laptops use a separately mounted power switch...double check that the ribbon cable is not damaged and is properly connected to the motherboard.
