I was struggling against my Android phone recently… While HTC instruction was pretty clear, I couldn’t understand how to “Reboot the device into recovery mode by holding down the HOME key during reboot”. I was under impression, that that one has to hold HOME key during a shut up, not during powering phone up. Luckily, I found a correct answer here (hold HOME during powering a device.)
After successful upgrade, my DevPhone showed a message that all the custom data will be wiped out if I press a Send key, otherwise upgrade won’t be installed. So, it was necessary to set up my phone for AT&T access once again.