Can't help you with the key fault but....!
I've had some issues recently with headlights flickering randomly as I drove along. I could hear the relays "chattering" as they were getting a signal to contact from somewhere.
That was the only issue until last week. Then the Bluetooth would randomly disconnect itself, a fault chime would "ping" and something would flash up on the dash - too quick for me to see what it was.
It all pointed to a BCM (Body Control Module) issue.
I decided to investigate....
As a disclaimer I would NOT advise doing what I have done unless you feel competent doing so!!!I decided to remove the BCM from the van and open it up to see were there any "dry" solder joints or obvious issues.
To open it you need to take out all the fuses - keep them in order so they can go back in the right place.
Then remove 4 Torx head screws from underneath.
Prise open, carefully, all the clips around the edge of the plastic cover and you will have access to the BCM - essentially a PCB (Printed Circuit Board)
When I took it apart I found some corrosion around some of the chipsets and other connections. Most of the connections are pressed into the board and not soldered. I found NO faulty soldered joints.
I cleaned up the corrosion with some electrical contact cleaner and a toothbrush and re-assembled the BCM.
Re-installed it in the van and since then there has not been one issue with the flickering lights, faulty Bluetooth etc.....
The only issue since then is that the heated screen has stopped working - both sides. I haven't had a chance to investigate that yet but hopefully it is something simple .
I hope this helps someone!!
Note: mine is a 2013 van and out of warranty so I didn't really have anything to lose by , carefully, investigating!!