Mini Convertible self-opening the roof

[MeldrewsMate]

A friend brought her daughter over today, claiming that said daughter's 2009 Mini Cooper convertible self-opened its roof whilst sitting untouched in their driveway. I had a look. Nothing came up on an OBDII scan, though there was an alarm on the dash,indicating that the remote key battery was discharged, and to recharge it she had to drive 'a long way'.
She had driven for 3 1/2 hours a couple of days ago!
The casing of the remote seems to be sealed, so access to its battery is not easy.

Whilst sitting in the car with the engine running we could hear the door locks regularly pulsing (the doors were already unlocked, so perhaps trying to unlock again?)
I stopped the engine, the lock pulsing continued.
I pulled out the remote key from its slot in the dash, shortly after which the roof started to open.

Some extra info: It's been raining today.

A quick t'interWeb search indicates that some people think it could be caused by a faulty BCU, or a faulty driver's door lock.

Any further pointers here?

MM

 

[Burnerman]

When the body control modules are faulty, the spanner service lamp stays on.....is it doing this?
John

 

[Old Salt]

Rechargeable batteries in those key fobs if they are the same as the bmw 1’s. Maybe new key time if its not holding a charge.

 

[MeldrewsMate]

@Burnerman no, it is not, and it has not been on throughout this investigation.
She has ordered a new key...£180, but youngsters seem to have a habit of not waiting for a thorough diagnosis, they jump at the first possibility. It does seem likely it's the key's rechargeable battery, but I am unwilling to break into the old one for fear of rendering it useless.

@Old Salt are you suggesting that the scummy BMW key will work in a Mini, that it's rechargeable battery is replaceable, or something else?

 

[TimboTwo]

The girl's got the right idea.

 

[Old Salt]

Not suggesting a bmw key, just that the new minis are made by bmw so sh1tty keys may be common throughout the range of cars. I dont think the batteries are replaceable in the rechargeable key fobs.

 

[MeldrewsMate]

Well,@TimboTwo , she seems to have been right this time, though only time will tell.

End of Thread, I believe. Thanks to all contributors.