Odd central locking behaviour

[snowfruit]

Hi all.
I’ve recently aquired a B5.5 Passat TDi Sport.
After a couple of weeks the central locking has developed some interesting symptoms.
The switch inside the drivers door will lock all the doors, hiwever the passenger door will reopen again immediately. The key in the drivers door opens the door, but does not operate the central locking. The key fob (with a brand new battery) flashes red when pressing the buttons, but eill not open or close the locks. However, if all the doors are shut, i open the boot and use the keyfob in the boot, it locks an unlocks all the doors...
The boot actuator had been unplugged by the previous owner. When i plugged it in to test it, its in need of replacement as it always returns to the open position. So forthe above symptoms, the boot lock is not included.

Any suggestions?