A couple more thoughts. You have previous posts about adding MC to the root system, so of course I'm wondering what has been touched or modified.
Your system is not usable, so the chances of getting out without a shutdown are small. I would copy the config (which may or may not be damaged) somewhere safe. It is located at /data/freenas-v1.db. I would export my pool. Then shutdown gracefully. Now there are two choices: You can reboot and see if it was a 'glitch' and things work normally. Or you can set your existing boot devices aside, and install clean. Now you have a good fall back position. You also have a system where you can import the pool, possibly the config, and either troubleshoot or just reconfigure depending on skill sets. Since we set the existing system aside, you can always plug in and go back to 'broken' should you choose to.