I was really hopeful for the power button trick but no avail.
I uninstalled iTunes and HTC Sync, and installed the HTC driver linked above with no effect.
Used a different USB Cable.
Tried repeating the process on my Linux server.
server user # md5sum recovery.img
server user # adb devices
List of devices attached
server user # adb reboot bootloader
server user # fastboot devices
server user # fastboot boot recovery.img
OKAY [ 1.209s]
OKAY [ 0.000s]
finished. total time: 1.209s
Same result, just boots like normal.