[Hero, G2 Touch General] alexmunroe:
I'm having to post this as a quote since I can't post outside links yet.

Make sure you have an SD Adapter to put your MicroSD in so you can plug it into a computer and access it.

I. Download and Install the Android SDK and USB drivers (If you already have this done, skip this section).

1. Follow our video procedure on HOW TO SETUP ADB/USB DRIVERS.

II. Create a “GoldCard” from a MicroSD Card

1. Put the memory card you want to use for the GoldCard into your phone.

2. With the memory card in your phone, click on Settings, SD and Phone storage, then click Unmount SD card. Once it unmounts, click Format SD card. (Please keep in mind that some memory cards don’t work, and this will erase all data on your SD Card so back all the data up first to your computer)

3. On the Phone, goto Settings, Applications, Development and then make sure USB Debugging is checked.

4. *Make sure you have installed the SDK and Fastboot correctly from Section I!!!

Plug the phone into the computer and then open the Command Prompt (goto the start menu and type in cmd in the search box). Then type the following with hitting enter at the end of each line.

cd\

cd\AndroidSDK\tools\

adb devices

(wait for the it to show a serial number underneath, if it doesn’t then reinstall the drivers from section I). Then type:

adb shell

cat /sys/class/mmc_host/mmc1/mmc1:*/cid

5. A code will display, write the code down (MAKE SURE TO WRITE IT DOWN EXACTLY!)

6. Goto this site, hexrev.soaa.me/, then put in your code you just wrote down into the text box and click submit. It will generate the code reversed and replace the first two digits with zeros automatically. Write that down and continue to step 9.

7. Now, on your computer, goto revskills.de/pages/goldcard.html and enter your email in the appropriate field and for CID enter the reversed CID you just got from hexrev.soaa.me/

8. Click continue and then you will receive your goldcard.img via email. Once it arrives save it to your computer.

9. Now, goto download.cnet.com/HxD-Hex-Editor/3000-2352-10891068.html?part=dl-HxDHexEdi&subj=uo&tag=button to download the HxD Hex Editor. Save it and install it to your computer.

10. Take your SD card out of your phone and put it into the SD adapter it came with. Then put that into your computer so it shows up on your computer as Removable Disk.

11. Open the Hex Editor (Run as Administrator if one Vista or Windows 7) and click on the Extra tab, then click on Open Disk. Under Physical Disk select Removable Disk (your SD card you just put into the computer). Make sure to UNcheck “Open as ReadOnly”. Click OK.

12. Goto the Extra tab again and click Open Disk Image. Open up the goldcard.img that you saved from your email. You should now have two tabs, one is the SD card (Removable Disk) and the other is the goldcard.img

Press OK when prompted for Sector Size 512 (Hard Disks/Floppy Disks).

13. Click on the Goldcard.img tab and click on the Edit tab and click Select All. Then click on the Edit tab again and click Copy.

14. Click on the Removable Disk tab (Your SD Card) and select offset 00000000 to 00000170 then click on the Edit tab and click Paste Write.

15. Click on File then click Save.

16. Close the Hex Editor.

17. Test what we’ve done:

Take out the memory card from the computer, then put it back in.

Try to open the memory card on the computer (Removable Disk), if it lets you, you are all set. If it asks/tells you to reformat the card, then try steps 13 – 19 again. If it gives you the same error again, then try a different memory card (Erlern said it didn’t work for him until he finally went and bought a Kingston 2GB card, then it worked on that card only).

18. Put the GoldCard into your phone and reboot the phone with the GoldCard inside.​

This was taken directly from theunlockr.com/2009/10/18/how-to-downgrade-your-htc-hero-so-it-can-be-rooted/ and as such I take no responsibility for any issues that arise as a result of using it.

I then flashed the official HTC WWE 2.73.405.5 release from here xdaforums.com/showthread.php?t=559622 . It took me a few goes to get it to initialise but once that was done I had the unbranded release ready for upgrading.

Once that was installed I set-up the phone again, set the date forward by a year and was then prompted to install the 1st part of the update.