Does anybody know why only the "unlock" portion of the key fob would work on my 850 Turbo?

Both of the fobs that I have for this car will unlock the car but neither will re-lock it...I have to use the key in the door and it locks all of the car doors, so I know that the relays are working.

 

If you can stop by your local Dealer they should have a device that they sit the remote on and hit a button. If the remote is working the device will beep.

 

turn the back with flathead screw driver / replace battery / but first
dismantel the fob and clean between the buttons and the circut contact
with acetone put back together and it will work cause you already prove this by one side working simple

 

if its both fobs you could try reprogramming.

Better than going to the dealer you could go to an autozone and they have a fob tester, you just point it and hit your button, in your case I'd hit the one not working, and see if they are transmitting (an led lights up if it sees the signal).

But, my bet is you could reprogram and they will work, there is instuction on the site somewhere for it depending on the year.