[Desire HD Q&A, Help & Troubleshooting] fairsimple:
Hi Everyone. By opening this thread, I hope I can 1) log my work, 2) get input from the wonderful people here, 3) benefit others who has the same type of brick. I have been reading/following/searching stuffs here for a while, and this is my first dirty-work-to-do. Please help me as much as you can. Thank you all!

How I bricked my Telus HTC Desire HD:

Phone has stock Android 2.3 and one day it keeps rebooting

Unlock bootloader by HTCDev

Didn't turn S-OFF

Flash _TOUCHRECOVERY__CWM_5.8.0.0_Touch_Recovery_for_DesireHD successfully

Flash cm-11-20131203-UNOFFICIAL-ace.zip successfully (after one failure) but phone is in boot loop

Unzip boot.img from the CM11 zip and 'fastboot flash boot boot.img' (as in [1]). The command didn't return anything, and I disconnect the cable after about 1m

Now the phone bricks, it doesn't boot to fastboot/hboot, charging LED never on. Connecting to PC shows a QHSUSB_DLOAD device.

The first thing I'd like to know is the root cause of my brick. Is it because the phone has S-ON, or because I disconnected the USB cable before getting the fastboot fully done. As [2] (which is for One X), the S-ON may not be an issue, then why the fastboot command didn't return anything?

What I got to work so far:

Install driver to my PC (QHSUSB_Drivers_(x64).zip from [4], thanks JSLEnterprises)

Enable the driver as test driver since it doesn't have signature (as [6])

Install QPST (QPST_2.7_378.zip, from [5], thanks darkspr1te)

QPST connects to phone and lists as type 'Q/QCP-XXX' which is in '*Download*' mode

As there is an 'HTC Unbricking Project' which doesn't have DHD in its supported phones list [3], I see the hope to unbrick my DHD without JTAG. I am not expecting to have a one-click solution like the unbrick project, and I am open to do some coding if needed, but I think I should be able to restore my boot partition (or multiple partitions) with QPST. And here I need your help:

1. What cause the brick? S-ON of the phone, or failure of fastboot

2. Do you think I can unbrick it just with QPST

3. If someone has a working Desire HD and uses QPST to backup its partitions to files, will I have its IMEI/CID/etc after download those files to my phone

4. Do you think I can manully build the QPST QCN download file from a stock ROM/RUU

Thank you!

[1] http://xdaforums.com/showthread.php?t=2533007 (HTC Desire HD > Desire HD Android Development > [ROM][UNOFFICIAL] CyanogenMod 11 Nightlies)

[2] http://xdaforums.com/showthread.php?t=1603791 (HTC One X > One X Android Development > [WARNING] Flashing boot.img on S-ON devices)

[3] http://xdaforums.com/showthread.php?t=1522351 ( HTC Sensation > Sensation Android Development > [UNBRICK] HTC Unbricking Project)

[4] http://xdaforums.com/showthread.php?t=1041153&page=2 ( HTC Desire HD > Desire HD Q&A, Help & Troubleshooting > [Q]HTC Desire HD QHSUSB_DLOAD driver[brick caused by rom manager sdcard repartition])

[5] http://xdaforums.com/showpost.php?p=33545892 (AT&T Samsung Galaxy Note I717 > AT&T Galaxy Note I717 General > [SOLVED]-[BRICKED]SHV-E160L Korean model)

How to calculate partition info in post #13, 15, 16 thanks darkspr1te

[6] http://windows7themes.net/windows-requires-a-digitally-signed-driver-windows-7.html

[7] http://xdaforums.com/showthread.php?t=2086142 (Hardware Hacking > Hardware Hacking General > [R&D][QUALCOMM] Using QDL, EHostDL and DIAG interfaces & features)

[8] http://xdaforums.com/showthread.php?t=905003

(HTC Desire HD > Desire HD Android Development > [GUIDE] How to downgrade 1.7x/1.8x/2.x to 1.32.405.6, with download of stock PD98IMG.ZIP)

[9] 7x30 HEX and MBN files in post#39 and partition.mbn and HxD HEX editor in post #48 (thanks mickeyasamoah)

[10] Qualcomm docs in post #87 and post #88 on page 9 (thanks darkspr1te)

[11] QFIT (flash image creation tool) in post #90 (thank darkspr1te)

[12] fixdhd.pl v20140228 in post #98 (based on qdloader.pl thanks JCSullins(Rootz Wiki)) v20140410 in post #161 on page 17

[13] MBN files from HP Pre 3 device in post #126 (thanks mickeyasamoah)

[14] Qualcomm development doc in Chinese and English. Need download file from https://support.cdmatech.com/login/, https://silver.arm.com/browse or https://developer.qualcomm.com/.

[15] Related post: Request for DHD backup and Qualcomm docs

[16] (thanks Gussta) Qualcomm processors and Snapdragon SoCs (post #139 on page 14), and Dual boot DHD with SD