I had the can't-open-the-damn-boot problem. I tracked it down to the release micro-switch & license plate illumination assembly. Seems some corrosion was causing current leakage which was enough to convince the control unit that the switch was permanently closed.
Before you crawl into the boot and start taking the door lining off I suggest you disconnect and then reconnect the harness connector under the parcel shelf. If the lock then opens then you probably have the same problem as me and you've saved yourself a cricked neck and a sore throat from cursing and yelling. Said from experience.
Props to eretron for posting the circuit diagram.
