Hi! I'm having the exact same problem after reflowing my logic board. But I found a way to always make it boot. - Unplug the battery. - Unplug the magsafe power cable. - Hold down the powerbutton for about 10 sec and continue to do that. - While still holding the powerbutton down, insert the magsafe power cable and hold it for another 10 sec. - Release the powerbutton after those 10 sec and make a "normal" press as if you would normally turn on your computer. If that doesn't work then try to remove one RAM memory and switch places and do the method that I told you.