[HD2 Android Q&A, Help & Troubleshooting and Genera] anrabi4:
FIRST OF ALL, I CAN NOT BE HELD RESPONSIBLE FOR ANY DAMAGE YOU DO TO YOUR DEVICE! PROCEED AT YOUR OWN RISK!!!​

Now that we got that out of the way...

I have noticed that some people`s Marketplaces simply refuse to update by themselves (exactly what happened in my case) and as most of the people visiting this forums are not tech-savvy and simply want a step-by-step guide to get things working, I decided no harm can be done by me posting this info.

Installing Android SDK revision 8

First of all, you will need to have Android SDK (and ADB of course) installed with the drivers ready to go. In order to get the SDK installed go to the official Android website and download the latest revision (r08 at the time I posted this). You can download any of those files, but I prefer using the executable installer so I can make sure everything is at its place. Now, there are two major flaws with this whole process which have almost made me quit the whole process several times, but I got them sorted out and will help you solve them aswell.

FLAW #1: After beginning the installation process, the installer will prompt you to download a JDK (Java Developer Kit) in order to continue installation. Hit the "Visit sun.java.com" button and download the latest Java SE (currently this one). But before proceeding be sure to download the 32 bit one, as the Android SDK only recognises this version. I know it`s not a big deal, but I spent about two hours trying to figure out what the heck went wrong and it became quite frustrating.

Install the JDK, then the SDK. Once Android SDK is done, simply go ahead and launch SDK Manager (you can find it in Program Files\Android\android-sdk-windows\) and when you get to choose the packages to install, simply check "Accept All" and click "Install". Once it`s done, it`s time to download the drivers. Click "Available packages", tick "Third party Add-ons" and under "Google Inc. add-ons" you should find "Google Usb Driver package". Tick it and click "Install". IF YOU GET AN ERROR SAYING THAT PERMISSION WAS DENIED AND YOU ARE UNDER WINDOWS 7, COPY THE WHOLE "Android" FOLDER CONTAINING THE SDK TO YOUR DESKTOP (OR ANY OTHER PLACE) AND REPEAT THE STEPS ABOVE. I know it`s quite rudimentary, but it does its job. Once it`s done, a folder named "google-usb_driver" will be created under Android. Be sure to correctly copy it to the original location in case you had permission issues.

FLAW #2: Ever since Android SDK r08, Google decided to remove the ADB files so now they have to be manually placed in the folder. I have uploaded them for you, so click here to download them. Once downloaded, extract the archive to the "Android\android-sdk-windows\tools" folder.

OPTIONAL: Go to Start Menu, right click on Computer, click Properties. The System window will appear, where you need to go to "Advanced system settings". Once there, click on "Environment variables" and where it says "System variables", look for PATH. Once found, highlight it and click "Edit..." then add the line "C:\Program Files\Android\android-sdk-windows\tools;" at the end. Click "Ok", "Ok" and "Ok", then restart your computer.

Right now everything should be working as expected. Connect your HD2 to the PC via USB and hope for the best. If the drivers are working and it is recognized as a HTC device, open a command prompt and type "adb devices". If you get anything such as "List of devices attached" followed by some code such as "0123456789ABCDEF device", everything is working well. Good job, you just correctly and completely installed Android SDK on your PC!

If not...

Check your device manager and if you see any devices related to your HD2 having problems, simply right click on them and update the drivers with the ones downloaded earlier in the "google-usb_driver" folder then reboot your computer.

We`re all set! ...What now?

The whole process is actually quite simple. First of all, download the new 2.2.6 Marketplace and put it somewhere accessible, such as your desktop. Open a command prompt and enter the following:

adb remount
adb shell
rm /system/app/Vending.apk

This will basically delete the old Marketplace from your device.

Now go to the folder where you placed the new Marketplace, hold down Shift, right-click and select "Open command window here". A command prompt should pop up at the exact location. Now execute the following command:

adb push Vending.apk /system/app

And that is it! Now restart your device and try to run your Marketplace, it will load for half a minute or so then it will start normally. Enjoy!

I know this is rather a tutorial for installing the SDK, but I figured it would be useful to let everyone know how I managed to solve my problem. In case I skipped any steps or you notice anything wrong/wish to add anything, please feel free to do so!

If you feel my post has helped you in any way, do not hesitate to hit the "Thank" button! :D