did you have a close look at the power light? It stays on and does not slight vary in color?
It probably hangs on loading the bootrom from the wifi module. Check that one. Otherwise I would say the mobo is toast.
Something might have broken inside it. Have many of those lying aroung. There good for spare parts only.
Also P6 connectors are replaceble you know. It is not an easy job but did it many times