To begin with, you will need:
- A copy of the firmware ROM you want to Flash (.exe or .nbh), you can download the latest official 2.03 ROM for Europe from here
- An unsigned version of Hard-SPL (allows you to install unofficial ROMs) - you can get version 1.93 & 1.40 from the downloads section
Make a full backup of your contacts, messages, files, documents, programs etc before flashing your HTC Touch Diamond.
To start, you will need to change your SPL (Secondary Program Loader - loads the OS) using the unsigned Hard-SPL. You only ever need to install Hard-SPL once.
Make sure you have disabled the Sleep & and Hibernate modes on your computer before attempting to use the Hard-SPL.
Make sure your phone has more than 50% battery.
To change your SPL with Hard-SPL (use the 1.93 version unless you have troubles):
- Connect your phone to your PC and set up an ActiveSync connection
- Then launch the RomUpdateUtility.exe program - it ask you to make sure you have established a connection. Follow the on-screen instructions, and when it shows you the SPL you are flashing to, it should say 'Diamond 1.00' or similar. (It will say 'OliNex 1.40' or similar if you use the 1.40 version)
- After you have agreed to everything, it will begin the process of changing your SPL. Do not disconnect your phone, turn your PC off or launch any programs while it is done.
- Once it is complete your phone will reset, if it restarts OK congratulations! You are ready to add your new ROM. If not, do not disconnect your phone, wait a while and the RomUpdateUtility will change to a recovery screen, just follow the on-screen prompts.
Once you have Hard-SPL on your device, you can install any ROM. There are various ways to flash a ROM (you can do it over the USB connection), but I will tell you the safest which involves flashing from your internal storage:
- Take your ROM, and if it is in .exe format, extract it using a Zip program such as 7-Zip or Winzip, and find the largest .nbh file
- Rename the .nbh file to DIAMIMG.NBH (all CAPS), and copy the file to the root of your device's internal storage. Use the file transfer mode to avoid any possible problems.
- Make sure your phone has more than 50% battery left. Now take off the back cover, and do a soft reset by pushing the stylus into the hole with the red button in.
- Within 3 seconds of doing that, press and hold the Back key (arrow pointing the the left) and the Volume down key. Keep them held down until a Red, Green and Blue screen is displayed (if you don't get the screen, soft-reset and try again).
- As soon as the Red, Green & Blue screen is displayed, let go of all buttons. The phone will now go to a grey screen with some options on it (if you get a continuous 'USB refreshing' text, you need to use a later version of Hard-SPL).
- Press the Power Key (on top of the phone) once when you are on the grey screen, your phone will now start the flashing process, this should take 1-5 mins depending on the firmware.
- After the process is complete, soft reset your device again and your new firmware should be installed.
I used this process to flash my O2 XDA Ignito from the 1.93 firmware to the official 2.03, and have to say the TouchFLO interface seems somewhat smoother, and programs launch faster.
There are a number of cooked/home-made ROMs available, see Diamond ROM development - xda-developers for more of them.
For me information on customizing your Diamond, take a look at: modmydiamond.info - Home