[T-Mobile LG G2x] Rainer1011:
Fixed: OS X Lion w/ VirtualBox XP SP3

I got my G2x fixed up. I followed the general process found on the original post (process by, I believe, speedsk8x?) but with a few differences.

First of all, I'll be very specific. I am using OS X Lion with VirtualBox 4.1 and XP SP3. This might work for other systems, but why not be as specific as I can :)

I followed the original process until the KDZ steps (step 7). I did have my .kdz file in C:\Documents and Settings\All Users\Application Data (hidden folder)\LGMOBILEAX\Phone\ It may not be there originally, but it will be created after the first run through (explained in a moment). Now for the process:

Go through step 8 and 9 normally.

9a) After the .kdz file unpacks and hangs on Call fn_StartUpgrade, it'll start the "CDMA: wParam = 2005 IParam = x" spam and stop on IParam = 5. After a few seconds, you'll hear the disconnect sound. Immediately unplug your device and wait a few seconds. If you hear a reconnect noise, plug in your device and it should start spamming and you can skip to step 9c).

If you don't hear the noise, plug in your device anyway. (I went through this process several times, so you might get lucky and it'll spam you again. If it does, skip to step 9c). Click the USB icon on the lower-right of the VBox window (or Devices->USB Devices on the top, but I never tried that). There should be a device called "LG Electronics, Inc LG Mobile USB Modem". If you select it, some warning should come up saying that it is being used by something else. If it does, click Okay and do NOT unplug your device. Shut down XP and we'll be going in to change a couple settings.

9b) After your XP is shut down, open up it's VBox settings. Go to the Ports->USB tabs and click the + icon on the right side. A device in the list that pops up should be "LG Electronics, Inc LG Mobile USB Modem". Click that device (you're adding a filter to VBox so XP recognizes the device instead of OS X. You might already have this setting since XP already recognizes the device. At this time, I have one LG filter). Click Okay and restart XP.

9c) When XP is booted, flash the stock recovery just to be safe and open the update app (if you haven't already, copy the .kdz file to C:\Documents and Settings\All Users\Application Data\LGMOBILEAX\Phone\). Load the .kdz file and launch the software update. Once you hear the device disconnect (when IParam = 5), immediately unplug your device and wait a few moments (you may hear the reconnect noise). Plug your device back in and it should continue spamming. If you get here, then great. You're where I was when I figured out the second half of this process :P

9d) The update will continue spamming until it gets to around IParam = 46. Here, it'll stop again and you'll hear the disconnect sound. Again, unplug your device, wait a few moments, and plug it back in. Click the USB icon in the lower-right again and confirm that clicking "LG Electronics, Inc LG Mobile USB Modem" comes up with a warning saying the device is already being used. Don't unplug your device and shut down XP.

9e) This step is pretty much the same as 9b. Open up your VBox's settings and go to Ports->USB. Click the + icon on the right and click "LG Electronics, Inc LG Mobile USB Modem". You should now have TWO (2) filters called "LG Electronics, Inc LG Mobile USB Modem". Click Okay and start up XP.

9f) Do step 9c again (reflash the stock rom, open update app, load .kdz, run update, unplug on disconnect sound [IParam = 5], wait a few moments, plug back in, let it spam). Once it stops at around IParam = 46, wait for the disconnect noise and unplug your device. Wait a few moments, and plug it back in (I didn't hear a reconnect sound after unplugging like in step 9c). It should start spamming again.

9g) Success (almost)! I didn't run into anymore disconnects, but it does take a while to get to IParam = 100. After getting to that point, it rebooted and did the usual LG screen, G2x screen and it all worked, although none of the data pre-upgrade carried over.

extra step 9h) Success!

This is the process I used. Hopefully it works for others and hopefully I explained it well enough. I'll check this for a little while to see if it didn't make sense to anyone. Good luck!

Edit note: If IParam = 3015, then I believe the update failed and won't spam anymore (this will probably happen for steps 9a and 9d).