I've been messing about with the phone all evening - downloaded that ROM image from the other thread and pulled it apart to look at the OS files etc - the standard break-a-new-embedded-linux-platform routine.
Anyway, if you hold down BACK when powering on, it enters the bootloader mode with a "FASTBOOT USB" prompt, which sounded interesting. I got a copy of the fastboot binary, and extracted the kernel and the ramdisk images from "boot.img" in the "HEROIMG_Hero_HTC_WWE_1.76.405.1_R3_WWE_release_si gned.zip" (using split_bootimg.pl).
Just as a quick test, I tried booting them with:
fastboot boot kernel.img boot.img
since the above just boots a kernel from RAM, and not actually flash it. Anyway, fastboot claims it downloaded and booted it ok, and the phone shows the "HERO" logo. Unfortunately that is as far as it gets. However, if I reset the phone, it boots perfectly fine from the kernel/ramdisk in flash (phew!)
Since it doesn't actually boot into android proper (and doesn't show up as a USB device), I don't know if (a) its showing the HERO logo, but failing the signature check, or (b) actually booting, but crashing 'cos the kernel/ramdisk aren't quite right. I'd guess (a) myself, but I'm new to messing with HTC bootloaders.
Anyway, in case they're useful, the details of the phone from the fastboot mode are:
HERO CVT SHIP S-ON
Jul 3 2009,15:22:21