Here is the history:
I bought the HDH to use as a wifi remote control using e-Control. It wouldn't work with the stock 4.4.1 OS for unknown reasons so I decided rooting it was in order. I looked at the options and found HTCdev as the easiest. On their site it said that I could root and flash new ROMs. However, so much is protected by S-on that nothing I tried worked. I was a Linux beta tester, downloading onto 30+ 3.5" floppies back around 1990 and have been employed working in IT or UNIX software design my entire career, so it wasn't like I was a complete noob. I then tried flashing a new ROM and it failed as well. Not only is S-on protecting files in partitions, but it protects the partitions as well. That information on HTCdev was a complete lie, S-off is a requirement for rooting or flashing a HDH. But now, here is where I get to where I don't understand what is happening... I tried flashing TWRP and 4EXT to the recovery partition so that I could work from there. All image flashes fail with "remote: signature verify fail", but they somehow destroyed the stock recovery partition in the meantime (not that it really matters). At this point I decided to back up and try AAHK2. I relocked the device and fired up aahk2_fastboot, however, at this point AAHK2 can do nothing as well. No unlocking, no S-off, no recovery install and no flashing. So now here it sits rebooting into fastboot, locked up where even the HTCdev code even fails to unlock it.