[Touch HD Windows Mobile ROM Development] duttythroy:
UserGuide on how to downgrade/ upgrade and Flash through Vista using USPL for my New HD Roms based on 1.54 SPL:

Thanks to CrackWhore:

Dummies guide for flashing 1.56 roms

This is my contribution to the community. I was getting a little tired of typing the same thing over and over in threads so I just wrote a very simplified "Dummies guide for flashing 1.56 roms" ;)

Ok here are very low-level steps to install roms that are based on a 1.56 HTC rom (for example Dutty's 2.7 and up). If you are at a point where you have already begun flashing and are now getting a green, distorted screen and having huge issues, that is because you have done the process wrong. You can simply start over with this guide. You can still place your phone into bootloader mode so you are ok.

A little clarification too- the entire guide is intended for users who have HardSPL flashed to their phones already. If you are running the stock SPL and have been using USPL to flash roms (which, if you are, is most likely 1.14.0000) then you do not need to do step (3) or (4) but I would still recommend doing step (2) before step (5) just to restore the factory default rom and radio to the phone before loading the new HTC 1.56 rom (just to avoid any issues). If your SPL is not 1.14.0000 then you should follow the entire guide.

Updating HTC USB Sync driver

(0a) If you have Windows Vista x64 then you have to reboot your computer before you start this. Right as it is starting back up spam press F8 and when a menu appears select disable digital driver signing and continue booting as normal. Microsoft tries to "help" (so they say anyway) us by not allowing signed drivers to be installed on this operating system but lacks to tell us this when we get an error trying to install one! Go to next step.

(0b) Place your phone into it's bootloader. Step (4a) explains how.

(0c) Follow these instructions

Download everything

(1) Download several things:

(1a) Original HTC 1.14 rom (based on 1.14 SPL) - For example: Ruu_BlackStone_HTC_WWE_1.14.405.3_Radio_52.49a.25. 26_1.09.25.14_Ship

(1b) HardSPL by OliNex

(1c) Restore Stock SPL 1.14.2

(1d) Original HTC 1.56 rom (based on 1.54 SPL) - For example: Ruu_BlackStone_HTC_WWE_1.56.405.1_Radio_52.62.25.3 4_1.13.25.24_Ship

(1e) USPL v 2.5

(1f) A 1.56 based rom- Dutty's linked here- Dutty's 1.56 roms (either 2.7 or 2.8 at the moment)

(1g) USB Drivers

Flash original HTC 1.14 rom

(2) Flash the rom from (1a) to your phone.

Flash original SPL (1.14.0000)

(3) Run HardSPLWrapper_Blackstone.exe from the HardSPL download in (1b).

(3a) Do not click any buttons on the screen when the application appears.

(3b) Extract the RUU_Signed.nbh from the Restore Stock SPL 1.14.2 download in (1c).

(3c) Copy RUU_Signed.nbh that you extracted and overwrite the one in the directory where you ran HardSPL from. If you get an error message saying that the file is already in use that is because you clicked one or more buttons in the HardSPL application window once it appeared. If that happens to you, exit from it, start it again, and DO NOT CLICK ANYTHING YET.

(3d) Now you can continue in the HardSPL application and follow it as normal. Basically what you are doing is flashing the stock SPL back to your phone by overwriting the HardSPL's .NBH file with the stock one.

Check SPL version

(4) Check your SPL version.

(4a) Place your phone into bootloader mode. Turn it off. Hold the volume down button while you press the power on button. When the bootloader appears it should show SPL v 1.14.0000. If it does go to step (5). If it does not something happened so repeat step (3).

Flash new HTC 1.56 rom

(5) Load the rom from (1d) to your phone. If when you try to load it you get a message about an invalid vendor ID go to step (5a). If it is successful go to step (6).

(5a) If you got the invalid vendor ID message you need to run USPL before you flash the rom from (1d) to your phone.

(5b) Place your phone into bootloader mode. Turn it off. Hold the volume down button while you press the power on button. When the bootloader appears it should show SPL v 1.14.0000. If it does continue on. Otherwise go back to step (3). If you are coming here from step (6) then the SPL version will show 1.54.0000. This is ok and is correct.

(5c) Connect your phone to your computer via USB. The bootloader should change from Serial to USB. If you have driver problems then download (1g) and update your driver for the HTC USB Sync and then try this step again. If you need instructions on this go to step (0).

(5d) Extract USPL from (1e) and open a command prompt window on your computer (Start -> Run -> Cmd.exe). In said window go to where you extracted USPL and run BLAC_USPL.exe. You may have to disable your antivirus for this. Some provide a false positive that it is a virus/trojan.

(5e) Your phone should reboot and return to the bootloader but saying SPL v 1.15.USPL and USB at the bottom. If it does not show USB after some time, disconnect and reconnect the USB cable from your phone. Once this is ready go to step (6).

Flash new cooked rom based on HTC 1.56 rom

(6) Run USPL. For instructions on how, read steps (5b) through (5e). If you are at this point and have already flashed the new HTC 1.56 rom your SPL version will show 1.54.0000 at step (5b). This is ok and is correct.

(6a) Flash the rom from (1f) to your phone.

(6b) Hard reset afterwards. For instructions on how go to (6e). Once or twice- up to you. Twice has been recommended.

(6e) Turn it off. Hold the volume down button and volume up button while you press the power on button. You should see a message saying "This operation will delete all your personal data, and reset all settings to the manufacturer default settings. Press VolUp to restore manufacturer defaults, or press other keys to cancel." Do exactly what it says...

Most important step here

(7) Drink beer after completion :D

This should cover it. If you can't follow this don't flash these new roms. For any help just reply.

I take no credit for this. All I did was simplify and spell out instructions from Dutty and a lot of other people, as well as combine a lot of spread out information and links. And if you want more information in general, please read the Wiki on 1.56 roms and the Wiki on Blackstone in general. You can also get information on USPL here and HardSPL here.

Edit 1: Added information on updating USB driver.

Edit 2: Added some clarification on SPL versions under step (5).

Edit 3: Added more information on updating USB driver.