Install HTC Sense 3.5 ROM Android 2.3.4 Gingerbread On HTC Desire HD [How To Tutorial]

DISCLAIMER: Redmond Pie is not to be held responsible for any loss of data as a result of the malfunctioning of your HTC Desire HD.
Backup your precious data before you begin. Although it has been confirmed to work, there isalways risk involved. Use Titanium Backup [Market Link] or simply follow Step 5.
Besides this, ensure that you have flashed ClockworkMod Recovery for your HTC Desire HD after installing and launching ROM Manager [Market Link].
Lastly, ensure that your phone is fully charged and that it has at least 400MB free on the microSD card.
If you haven’t guessed yet, yes, your Desire HD must be rooted in order to flash the custom ROM.
Step 1: Download RCMix3D_bliss_v1.2.zip from here [MultiUpload Link]. If you’re following this guide considerable time after publishing, head over to this link to download the latest version of the ROM.
Step 2: Connect your HTC Desire HD to your PC with a USB cable and transfer the .zip file you download in Step 1 to the root/parent directory of your phone’s SD card. Once transfer is complete, disconnect your phone.
Step 3: Assuming that you have flashed ClockworkMod Recovery, open up ROM Manager and tap on Reboot into Recovery.
Step 4: Your phone will reboot into ClockworkMod Recovery (CWM). You can navigate it using the volume up/down keys, home/back button and power button.
Step 5: In CWM, scroll down to backup and restore to make a backup of your Desire HD’s current state. This will take time, so be patient.
Step 6: After backing up, you will be taken back to the main menu of CWM. Scroll down to wipe data/factory reset > yes — delete all user data. From main menu, scroll down to advanced > wipe dalvik cache and delete dalvik cache.
Step 7: Now this is where we flash the Sense 3.5 ROM (based on Android 2.3.4 “Gingerbread”): Scroll down to install zip from sdcard > choose zip from sdcard > RCMix3D_bliss_v1.2.zip. The custom ROM will now be flashed on your Desire HD.
Step 8: Once flashing is complete, you must now reboot system from CWM.
If you followed the steps correctly, your Desire HD should now boot into Sense 3.5 ROM based on Android 2.3.4 “Gingerbread”.