Before anything is said, i've tried a new battery & i followed the syncing description to the letter & still no joy.
The actual key will unlock/lock the door. It'll also start the car perfectly fine. It's JUST the remote which wont lock/unlock the car (on the spare key). The remote on my main key works perfectly fine (albeit the battery is on its way out finally, but that's nothing).
I opened the remotes up. Both have that weird shaped black chip in place.
There is a difference though. The innards of my main (working) remote look all secure. As you can see from the following pic....
The innards of the duff remote though aren't looking so secure. The battery housing has to be held in place by blu tac, or it just falls out.
I wonder if the contacts to the PCB have snapped (i don't know how it's fitted, but i'm guessing some thin metal contacts??). This is my only guess & it's just a wild one at that.
Oh, the pic.......