Download and flash your ROMs
Yes, I said ROMs - if you want to debrand your phone, you will need to download two sets of ROMs. If you're just updating and not debranding then you'll just need to download one ROM.
Download a ROM which is by the same network as you're on (for example if you're phone is currently locked to Orange UK then download RUU_Mozart_Orange_UK_1.22.061.10_Radio_5.50.09.18_ 22.24.50.09U, by ansar. - do not download 1.30!).
Open up ActiveSync/Mobile Device Center
Flash this ROM to your phone (you may not need to do this step, but most users will).
Turn your phone off.
Put your phone into Bootloader Mode - this can be done by pressing and holding the Volume Down Key & Power Button.
Plug your phone into your PC, hopefully a HTC USB driver will install.
Once the driver is installed your phone should display USB mode.
Extract the zip file and then run the exe file
Run through the update process
When your ROM is flashed, your phone will want you to customise it - just do the basic stuff.
Download the ROM you would like to flash (e.g. RUU_Mozart_HTC_Europe_1.30.401.01_5.54.09.21_22.33 b.50_RELEASE).
Extract the unbranded ROM zip file and then extract the exe file (WinZip will not do this - try 7zip or similar).
Copy the RUU_signed.nbh from the unbranded ROM
Extract the branded ROM exe
Paste the RUU_signed.nbh from the unbranded ROM to branded ROM
Plug your phone back into the PC in bootloader mode
Run RomUpdateUtility.exe file from the branded ROM (but with the unbranded RUU_signed.nbh file)
Follow the steps...
Et voila, you'll have (if all goes well) and unbranded ROM installed
Last step, plug your phone back into your PC and run Zune. Your phone should receive the latest cumulative update.
