I would double check to make sure that the data connector is
properly seated. Also, you may want to take a close look
at the connector on cable and on board and inspect for damage.
Might even want a magnifier to make sure.
Also, may want to check around that whole area for any accidentally
dislodged connectors and generally inspect for any debris.
for the fan issue, if you have something like iStat Pro, what temperature readings
are being displayed. If some temperature is really high causing the fans
to spin up, this could indicate either a damaged temperature sensor cable
or a fried chip that is cooking.
If all "appears" well, check System Information to see what is present
on the busses and also for wireless stuff. If things are missing there,
then run the Apple Hardware Test (http://support.apple.com/kb/HT1509).
This should tell you if you have a logic board problem.