Hi, I'm a little late to this party - but a very interesting thread. I've had my battery replaced at a local garage, and since then, the boot cannot be opened, manually or automatically. Its gone back to the garage but they are struggling to find any reason for it - found no obvious electric faults. Interested to read about this happening to some people in the cold/damp. In the three weeks or so before we had the battery changed, the heater broke (coolant leak - now fixed) and I noticed a lot of condensation forming on the inside of the car. I'm wondering if this has led to the problem. It seems that for a few people, this issue rectified itself when the weather improved.
Herbie, if you still have the information that pertains to this issue - I'd be grateful to have a look. I might get my car back this weekend and warm it up for a good while and see if that does anything.
Thanks.