Re: FF 400 goes into "loop" (endless beep sound)
I would be VERY careful attempting to solder anything on your computer's mobo. You MUST HAVE a calibrated iron set to a specific temperature with a VERY fine tip. Something like a Metcal iron would be easiest since there are a variety of tips that all come pre-calibrated and I have never seen that iron burn anything. Also, you will want to use a good ROHS "no-clean" solder or even better "water wash" solder (this means that after you solder you have to wash all of the flux off.) This is the best most professional way to solder, because it removes all of the flux from the pcb, which can degrade the pcb, especially in hi-temp situations.
Remove the battery (both the main battery and the watch battery) AND WAIT 45 MIN. Then, solder your header back on to the board. Wash the area with a Q-tip and some rubbing alcohol followed by a q-tip with some DISTILLED water. Let air dry for 2 hours, or dry with hairdryer from a distance and let sit 30 min.
Most computer mobos are many layer pcbs and use surface mount components. If this component is surface mount, you are probably out of luck. Plus, the board is pretty thin and will heat up quickly, making it easy to damage other components and even the board itself.
If it is really broken and not just a misunderstanding of how the connector works, I would highly recommend taking it to an apple authorized repair center. If it has applecare, just put it back together, take it in and tell them it's broken. They will quickly find the problem and should repair that sort of thing for free.
Don't let on that you were messing around in there, but unless you were using a screwdriver to remove the fan connector from the mobo, components coming unsoldered under regular use (the connector should always release before being ripped off the pcb) screams manufacturing flaw, and I suspect that any tech would see that component hanging off and say, "damn, that just came right off"
Whatever you do, be very, very careful,
Brian