Is there a way to do it without downgrading? Otherwise how do i downgrade. And can I restored my nandroid of my current stock rom afterwards?
Right to have created a nandroid backup and have clockworkmod recovery image installed your already rooted so no downgrading is necessary. Just use the ENG S-OFF tool supplied in that link.
The steps you need are:
1.Connect your phone to a computer (make sure you have USB Debugging enabled. Connect charge only!)
2.Open my "Desire HD easy s-off.exe", click "S-OFF it"! Allow possible SuperUser request on your phone.
3.There could be force closes after the process, just reboot and everything will be fine.
4.Done. (Remember to click the thanks button)
Now that your device is S-OFF, and you can get Rom manager from the market, which will install a ClockWorkMod recovery for you. Just open it up and tap "Flash ClockworkMod recovery".
From what I've gathered of this thread is that after installing ARHD you couldn't get out of recovery and reboot properly, so I'm presuming you did a format and factory reset and restored your nand backup of your stock ROM to continue using your phone?
If thats the case ensure you download the tool and follow those steps above.
Without ENG S-OFF Clockwork will not work properly. Once thats done reopen ROM Manager again and allow superuser requests then ensure your running the latest Clockworkmod and if not update it first.
Then with the latest ARHD and superwipe.zip on your SD card boot into recovery again and flash by choosing install from sd card. First choose superwipe and then proceed to flash the ROM zip. Another thing you will need to do to ensure you get the best performance afterwards is install the latest recommended radio.img.
Let me know when you get to that stage as I can give you everything you need to make it a simple follow the instruction on screen process.
All of that above will not work unless you have the superuser app in your app drawer and root access first. No downgrading should be required if you already have ship s-off.