The folder structure was wrong, in fact I don't understand why it ever even showed up in the Tools > Board menu for you with that structure. It didn't for me. I fixed the folder structure, corrected a mistake I made on the protocol, and fixed where you had forgotten to add the arduino reference to the variant values for the other two boards, which probably wouldn't have mattered if you're only using blue. The updated folder is attached, just replace your current folder with the one attached.
As to why the Arduino IDE won't start, I can't reproduce this. You may have a separate issue. If that issue persists after installing this new version try moving the HPs folder out of the hardware folder and see if the IDE will start then. That will show whether the HPs boards package is the cause of the issue.
hardware.zip (21.8 KB)