If You want to downgrade Desire Hboot 1.03, then using revolutionary to s-off, please follow the instructions .
1. Download tools package (attached files)
2. Download this HTC Official ROM (RUU)
3. For branded phones create GoldCard.
4. Extract the tools any where at your computer.
5. Run RUU and wait to appear Android rom update utility screen.
6. Go to Temp directory on C drive on your computer and find folder that RUU extracted in it.
7. Copy the rom.zip and paste it to sdcard and rename it to PB99IMG.zip
8. Connect your phone to computer via USB as charge only and enable USB debugging and Unknown Sources.
9. Run cmd.exe on tools folder that you download and extracted it and Execute these commands:
adb push flash_image /sdcard/flash_image
adb push zergRush /data/local/zergRush
chmod 755 /data/local/zergRush /data/local/zergRush
[**] Zerg rush - Android 2.2/2.3 local root [**] (C) 2011 Revolutionary. All rights reserved. [**] Parts of code from Gingerbreak, (C) 2010-2011 The Android Exploid Crew. [+] Found a GingerBread ! 0x00017118 Sending 149 zerglings ...[ * ] Trying a new path ...[ * ] Sending 149 zerglings ...[ * ] Trying a new path ...[ * ] Sending 149 zerglings ...[ * ] Trying a new path ...[ * ] Sending 149 zerglings ... [+] Zerglings caused crash (good news): 0x401219c4 0x0054[ * ] Researching Metabolic Boost ... [+] Speedlings on the go ! 0xafd260a9 0xafd39f9f[ *] Poping 24 more zerglings[ * ] Sending 173 zerglings ... [+] Rush did it ! It's a GG, man ! [+] Killing ADB and restarting as root..enjoy!
cat /dev/mtd/mtd0 > /sdcard/misc.img
cat /sdcard/flash_image > /data/flash_image
chmod 777 /data/flash_image
adb pull /sdcard/misc.img misc.img
17. Open misc.img in the current directory, and change line 11 which contains the version number of your current ROM. Change it by number of the future ROM you want to install(Find at Android rom update utility screen after run RUU)
Changes will appear in red. Save the file to misc0.img.
adb push misc0.img /sdcard/misc0.img
adb shell /data/flash_image misc /sdcard/misc0.img
19. Wait for detect and check the Update Package.
20. After checking package, press vol-up to begin update process, IN FIRST TIME AFTER PRESSING VOL-UP YOUR PHONE WILL RESET AND DO NOTHING, YOU SHOULD DO AGAIN FOR STEPS 18,19,20.
The process will flash your recovery partition back to stock
This process will wipe all the data from your phone
The downgrade installs an official stock HTC ROM with Hboot1.02 (You can s-off with revolutionary and after it You can flash any version of Hboot)
Your sdcard should be fat32 formatted
Creating a goldcard
IF YOU CAN NOT DOWNGRADE HBOOT,WITH THIS TUTORIAL, PLEASE READE THIS POST