I've sniffed around at the BM cameras for years as I've been lacking a "runaround" camera for little projects for a long time...I have an A7S which is obviously capable but I don't like having to dress it up with a bunch of outboard stuff to shoot video. The form factor of the original BM camera was a dealbreaker for me. The originally URSA had interesting notions but I wasn't fully convinced. 4.6K Mini was mildly enticing but once you've tasted the allure of high ISO as others pointed out, it's tough to live at 800 for night/interior work.
I will say that as a company, they are getting better (I think) at supporting gear after the sale. Earlier on they seemed to have had a smash-and-grab philosophy that turned me off. Example: I have two of their heavy-duty SDI to HDMI converters that both failed, and they were just months out of warranty. They told me they couldn't do a thing for them, no service outside of warranty. Anyone want 'em?! They make lovely paperweights.
That said, I own a bunch of their gear which hums along without issues.
I'd take those converters from you, be worth the cost of shipping to tear them apart. Having a few of those, I'd guess that the heat caused a poor quality solder joint to pop (or something like that). They do get incredibly hot.