[Desire HD Android Development] makbil:
First of all, you need to have these installed before starting.

1- Android SDK http://developer.android.com/sdk/index.html

Unzip the file and copy the whole folder to the root of your C: drive

2- Java JDK 6 http://www.oracle.com/technetwork/java/javase/downloads/index.html

Install from the executable.

3- If you have problems with the PC not recognizing your DHD, you probably need to install HTCSync which also installs the drivers.

Make sure that you have downloaded all the required files from post #1.

Before going any further, make sure that your phone has Radio S-OFF - this is very important:

I used One Click S-OFF which worked well for me.

1- Download and install ROM Manager from the market.

2- Run ROM Manager and select the first option: Flash ClockworkMod Recovery.

Be careful, even if there is a problem with the operation, you will not see a notification on screen, so if in the next step you can't reboot into recovery from the second option, something has gone wrong. Restart phone, hold vol down + power and see if you get S-OFF at the top right of the screen. If you see S-ON, then go back to applying S-OFF.

(At this point, if you did everything correctly, you will have radio S-OFF. Eng S-OFF and Clockwork hboot in place)

3- Download the update file rename to update.zip and copy to the root of your SD card.

4- Reboot into clockwork recovery (from the ROM Manager) and choose apply update.zip

5- Reboot.

At this point everything should work except for wi-fi. Don't worry about root yet, check the version info in about phone.

Now we have to flash the kernel to fix wi-fi.

Re-flashing the kernel

You hold vol-down + power to reboot into bootloader, select fastboot mode and stay there

Go to the "tools" folder of your Android SDK folder on your PC

Open a windows command prompt window (All Programs->Run->cmd), go to the "tools" folder of your Android SDK folder on your PC and write "fastboot flash boot boot.img" (fastboot.exe is in that folder, if you get an error with some missing files, they are elsewhere in the Android SDK, copy them to the tools folder). This process took a few seconds on my PC.

Now for getting Superuser back:

Restoring SU:

First, make sure you uninstall the superuser program from your DHD <- This is very important!

Download the old su package from here

unpack files to SDCARD

boot to Clockwork recovery (Vol down + power) - If you are having a problem here, start your phone normally, then press the power button and select "restart". As soon as you confirm by pressing "yes" keep holding Vol- + power. You will get to the bootloader screen.

On your DHD: (you can scroll with the volume key and use the power button as the "enter" key)

mount /sytem

mount /sdcard

Connect DHD to your PC through USB. Since it is in bootloader mode, nothing significant will happen at this point but you should hear a beep or two indicating the PC recognized a device.

Now go back to your PC. Open a command window and go to your Android SDK platform-tools folder.

In the command window, type adb shell (The file adb.exe should be there)

You should see the # prompt. This means you are a superuser.

Type:

cp /sdcard/su /system/bin/

cp /sdcard/Superuser.apk /system/app/

ln -s /system/bin/su /system/xbin/su (In the ln... command I got a message that file exists but that is OK, it still works.)

chmod 06555 /system/bin/su

exit

Now go back to your DHD, from the menu:

unmount /sytem

unmount /sdcard

Reboot DHD from the option in the menu. Now you can unplug the USB cable :)

Done. Everything works for me without any issues, I have the new firmware and root :)

Flashing a new radio is much easier since you have already set up everything that's required.

First, check this thread and choose a radio that you like. It may be a good idea to read that thread to learn what the experiences of the users are.

Just for the sake of distracted users :) I will mention again that

you need radio S-OFF and Clockwork mode recovery installed

.

- Extract the radio.img file to the /tools folder of your Android SDK

- Connect your DHD to your PC with the USB cable. Reboot your DHD to recovery mode and select fastboot - you should see fastboot in red at the top of the screen.

- From a windows command prompt window, browse to the /tools folder of the Android SDK

- Once in the /tools folder, type (without quotes) "fastboot flash radio radio.img", or just copy/paste this line using the top left menu - edit -> paste

- Wait until the send and write operations are completed (as reference, this took 79 seconds on my notebook). You can also see the progress in the top right of your DHD's screen in the red vertical bar.

- Reboot your device

The first boot time takes a while, don't panic :)