so it have no signal, thats sad. if u still wanna fix it urself, then the best is still to mess around with the internal connections, i think if it was already good, then its just an erroneous connection somewhere.
on irc, currently someone have a similar issue with a brand new machine, maybe u could join to it if anything valuable comes up there in the meantime. (freenode -> #purism) btw the symptoms that the other person have is this: " disturbingly, the wifi LED comes up even if the kill switch says its off"