Just follow the steps on htcdev.com, and at the last step you will have a factory reset. So, please make sure you do a backup before attempting this unlock trick. (Thanks to NilsP for pointing this out)
Bootloader unlock will grant perm root and possibility of flashing customized roms.
Note: S-on remains
bootloader unlock will VOID your rezound's WARRANTY, I am not responsible for any damage it may cause
HTC Sync (Windows Only)
HTC Super Tool
Enable USB Debug on Rezound
Use Charge Only mode when connected to PC
Exit HTC Sync on PC
1. Go to HTCDEV website: http://www.htcdev.com/bootloader/
2. Click on "Begin Unlock Bootloader" (create a user if you don't have one)
3. Use HTC Super Tool in the [Prerequisites] to generate your token. (Or, alternatively, follow the instructions step 1 through step 10 on htcdev.com)
4. In step 10, when posting your token, make sure you remove the blanks preceding each line
5. After you receive your Unlock_code.bin in email, follow step 11.
6. Now your rezound should reboot and you have your bootloader unlocked.
Now you are unlocked. You can follow the following threads to obtain perm root, flash recovery, flash new kernel, and overclock.
[Guide] You are Unlocked. Now What?
[GUIDE] Super-noob guide to unlocking, rooting, and flashing Ziggys kernel
7. After unlocking your bootloader, use this one to get perm root:
One Click Perm Root (Thanks to NilsP)
8. Flash the recovery if you need.
[Recovery] Amon Ra style vigor
[Recovery]ClockworkMod Recovery 18.104.22.168
scrosler kindly provides a tool to flash the recovery or boot img.
You can find it here
9. Flash Deodexed ROMs:
Clean ROM 1.0 from scrosler
RezROM v1.0 Beta from lllboredlll
Questions about flashing ROMs:
Possibility of flashing ROMs (Thanks to scrosler)
To uninstall the bloatware, try ROM Toolbox