I think??? the E70 has the GM module components are included in the footwell module which may also control other accessories that the earlier E39/E53/E46 did not have.
I think it really boils down to 2 possible problems.
1. The drivers door latch assembly itself
2. The relay for the driver door latch on the Footwell module.
Here is what I recall from the GM5 problems, the relays would get pitted and almost always have a problem UNLOCKING, but locking would usually work. Often temperature dependent as well.
You might read over the info at the
www.bmwgm5.com site. As I recall if the interior lighting came on, but he door did not unlock the problem was usually the door latch assembly. If the interior lighting and the door did not unlock the problem was usually the GM5 relay?? Double check this of email Scott at
www.bmwgm5.com and tell him your symptoms. He is the one guy on the planet that seems to have the Central Locking figured out for at least the older chassis. But I assume as the newer chassis age, we will soon see similar problems with the E70 and other chassis.
The fact you stated that the door will Lock with the keyfob, but not unlock sounds very much like the GM5 relay problem.
It is very hard to isolate the door latch assembly vs door lock relay problems. They are so inter related it takes a lot of testing and knowledge of how the system works to pinpoint the exact problem the first time.