Assuming you have not figured this out yet or tossed it, if the system is getting power to the board but not sending a signal to the monitor, you may have blown caps on the mother board. There is a string of them about 1/2 to 3/4" tall next to the processor. One or more may either be expanded or blown.
Crack the case and check them out. If they are blown, I suggest replacing the mother board, since a normal soldering gun will not get hot enough to remove the caps and allow replacement.