BEFORE WE BEGIN, SOME TERMINOLOGY:
Unlocked Bootloader: HTCDev website will help us do this. It's free. It allows you to flash a recovery and signed boot image, which we have. It does not allow you to flash unsigned images.
S-On: Security on. This is how our phones come stock. Htc will not allow us to flash unsigned images because of this.
S-off: once someone achieves this for us, it will allow us to modify anything and everything, signed or not. We can flash new boot image and radios without worry of version number or signature.
Root: Allows you "administrative access" to your device, to move files and do certain things. However, our phone also has...
System Write Protection: HTC included this in the kernel, and it basically means that unless you have a kernel or boot image that gets around it, any changes you make to the system partition (aside from flashing in recovery) won't stick through a reboot. Essentially they will be temporary in an effort to preserve the phone. We don't like this.
Now then, with that out of the way...
1) HTCDev Bootloader Unlock: Under "Select Your Device", scroll ALL THE WAY TO THE BOTTOM, and choose "All Other Supported Models". I know it works, because I just did it. IT WILL WIPE YOUR DEVICE DATA. If you want the data backed up beforehand, turn on USB Debugging and use this command through adb to make a backup:
adb backup -apk -shared -all -f C:\desirebackup.ab
DISCLAIMER: ONCE YOU USE THIS TOOL, YOUR DEVICE WILL HAVE THE ROOTED ENGINEERING BOOT IMAGE, WHICH CANNOT BE REVERSED. THERE ARE NO SIDE EFFECTS TO THIS IMAGE EXCEPT THAT IT SHOWS A DISCLAIMER ON YOUR SPLASH SCREEN WHEN YOU BOOT THE PHONE. THIS CANNOT BE CHANGED UNTIL WE GAIN S-OFF, WHICH HAS BEEN ACCOMPLISHED, BUT IS NOT YET PUBLICLY AVAILABLE. IF YOU ARE OK WITH THIS, PROCEED.
IF V3 DOESN'T WORK, HERE IS VERSION 2.1: Download ClearD's Root Tool V2.1. THIS VERSION INSTALLS ENGINEERING BOOT IMAGE AND JMZ KERNEL.
Return to Stock (AT&T ONLY) :http://dl3.htc.com/application/RUU_A...6_signed_2.exe
This ruu will bring you back to complete stock, version 1.50.502.7. It has to be run through Windows, and you have to have a locked bootloader to run it. If you're unlocked, you can relock it in fastboot with the command:
fastboot oem lock
Older root tool version 1:
Download ClearD's Desire 610 Root Tool V1. This version does not contain the engineering boot image, and needs it to work fully, thus is buggy and probably won't root you with one click. It will fail to adb remount, which will fail to auto install the zip files in recovery. If you've already flashed the engineering boot image, then it will work properly without issue. Otherwise, it'll place the root zip files on your phone, but you'll have to flash them manually in recovery.
2) Recovery: After you're unlocked, download TWRP recovery from this thread, rename the image file to "recovery.img", and flash through fastboot with the command:
fastboot flash recovery recovery.img
3) Insecure Boot Image and Root: Once you have recovery installed, the rest is easy. In recovery, if you try to reboot back into the rom, it will ask you if you wish to root. Select yes. It will do the rest I believe, and install SuperSU when you boot back into the rom. You'll also want to download and flash JMZ's insecure kernel, which unlocks the system file lock that htc places on their newer devices. Once flashed, you can then change system files and the changes will stick through reboots.
Once unlocked, download the root zip provided in this thread, then open it. We can't just flash the zip file because most of us have an updated rom version than the one it was intended for, and I'm not sure how to fix that. But no bother. Pull out the boot image file, and place it somewhere you can find it. I put it right in my MiniADB/Fastboot folder for easy access. Then, you need to flash it. Here's how:
fastboot flash boot boot_root.img
To restore your backup you made before unlocking, use this in adb:
adb restore C:\desirebackup.ab
Special thanks to:
-JMZ (Recovery and Kernel)
-Deez_Troy (officiating recovery)
-AdriVelazquez (Insecure boot image)