@susamlicubuk i know that thread is a year old, but have you got the rest of the ethernet ports working?
While researching for a similar issue with another appliances I looked at the download you linked in the third post.
In that download there is a watchdog driver for linux and FreeBSD for resetting and bypass-ing the system.
Compiling it for pfSense will be complicated and I'm of no help with that. It's easier on plain Linux or FreeBSD, the driver itself looks quite simple but it's references FreeBSD 8. Not sure how easy it can be compiled for a current FreeBSD.
Have you tried compiling and using the driver and userland tools?