All -
Thought this recap might come in handy to some who will (inevitably) face the same issue.
2005 XC70 w/115k.
Sometime in the late Summer, my driver's side window, locks, mirrors, and power locking mechanisms all failed. I figured it was the Driver's Door Module, which the dealer confirmed with VIDA when I took it in for the timing belt. They quoted ~$700 to fix in parts and labor.
After reading the threads on this forum, I decided to order a replacement from eBay, swap it myself, and take my chances knowing that at worst, I'd have to take it into the dealer to have it re-initialized.
I purchased a nicer unit on eBay for $50 - same part number, from an S60, same manufacturing date as mine. Dropped the door panel (those tabs around the edges can be difficult - punch the middles all the way through with a small eyeglasses screwdriver then they come out with just your hands) and swapped the unit. Did the whole battery disconnect/reconnect procedure, leaving the key in position II, etc.
No dice.
Decided to bite the bullet and take it to the dealer for re-initializing. Well, to ask my wife to take it to the dealer, since they inevitably treat her better than they treat me. Left it for the afternoon and was told upon pick up that they couldn't initialize it and a blank unit (read:new) must be installed. Same quote to do that, but no charge on the failed re-initialization.
In the meantime, I had disassembled the original unit, cleaned and reconnected the ribbons inside the switch, and cleaned the contacts. Before pulling the trigger on a new $300 part + dealer time, I decided to try it one more time just to be sure.
Dropped the door panel, and while I was swapping the cable harnesses, I noticed that on the larger harness, one of the wires (red) was hanging loose from the harness. As soon as I plugged that wire back into the harness (firmly), I heard the solenoid for the lock engage - and after re-installing the original Driver's Door Module, it was good as new!
Moral of the story: check the small things - and be aware that those wires can come loose from the harness, and can be reinstalled by just pushing the back in until they're firmly seated.
Now I've got a backup DDM, and $700 more dollars in my pocket, plus a wife who likes not having to pull forward at the parking garage to get her ticket.