Golf GTI Ed 30 won't lock

[Trobbler69]

Hi all, I have a fault I could do with some help finding:
My car won't lock - specifically the driver, passenger and both rear doors.  Both keys have new batterys and are communicating with the car, the following symptoms are the same pressing the key buttons, or using the button inside the car:  When I press 'unlock' I hear a click, lights come on as usual.  When I press 'lock' I can hear another click, like something is trying to lock, but nothing actually locks apart from the boot, no indicator flash.
I have pulled fuse 12, and it all seems fine. 
The alarm seems to 'arm' itself; a red LED comes on a solid red for a moment on 'locking' then flashes for a min. Then, when I open the door the lights flash like an alarm is going off (no siren, potentially a separate issue, thoughts on a postcard...).  I then put the key in the ignition and all is reset.
When I put my ear to the drivers door lock when pressing 'lock' I can hear a click, potentially also on the driver side rear door, but no clicks at all on the passengers side. 

Other than that, the car electricals are A-ok, everything works.
The car in question is a 2007 Golf Mk5 GTI Edition 30 - As far as I can see the whole car is standard. Let me know what other specific info might help.
Ta

[pudding]

Maybe the central electrics module thinks a door is open, hence not locking.  Have you got the highline display with the boot, bonnet and door animations?

You won't have 4 x door modules go down at once, so it's going to be something simple like that.  I believe the door 'switch' is part of the door latch module, so probably worth getting the scan tool out and it'll tell you which one.

[Trobbler69]

Thanks for the response.  After a driver yesterday one of the rear doors decided to lock, but then wouldn't unlock. 
I agree with you, its unlikely that x4 latch modules have failed. Weirdly, when attempting to lock, there is a sound like the car is trying to lock, and the boot does lock.
When deliberately locking the door with the emergency buttons and then using the key in the door, there is a positive CLUNK. 

Could this issue just be a poor battery? The car starts ok, turns over a tiny bit laboured if i had to be picky. Anyone else experienced poor locking when the battery is poor?  Surely if the battery can turn over an engine it can lock the doors!