Nov 28, 2010
So the time has come when I'm upgrading to a nexus s, so I want to sell my hero but it needs to be on the stock rom, how do I go back to the stock rom?
You should just be able to download and run the firmware RUU from HTC's website:

HTC Hero - Software Download

Make sure to pick the one with the correct branding, if that's important to you.

Note that this will install 1.5, so you'll need to re-do the OTA update.
I have downloaded it but it doesn't pick up my phone? when I connect my phone it only gives the choice of usb storage.
Hmm, the USB storage thing isn't really related to the firmware install.

Make sure you've got HTC Sync installed (top option in the list), then you need to download one of the 'ROM upgrade' files below it - the one you need depends on whether or not your phone was branded. Plug your phone in via USB and run the rom upgrade file you downloaded on the PC and see where that gets you. Report back with any problems :)
ahh, I see what I was doing, I was making it usb storage when I should have just left it, Ive now got it working, Thanks for your help :)