Temperature for making bone broth in slow cooker
It's almost certainly not ruined, in the sense of being unsafe or undesirable to eat. A higher temperature can actually increase the extraction of collagen, which is generally desirable for stock/bone broth, though it could also damage some nutrients and more delicate flavors. Given the amount of collagen to be extracted from beef bones, a 19-hour cooking time is certainly not excessive, and you could probably go even longer.

The bigger concern is really with the slow-cooker. A noticeable boil, even just a few bubbles, indicates that the actual temperature is probably on the high end of the manufacturer's given range. If an automatic shutoff also didn't work, that might indicate a faulty component; it sounds to me like the heating element might not be shutting off appropriately to maintain an accurate temperature. That may make the appliance less safe to run unattended and will make its behavior less predictable whether you use it for broth again or something else.

Personally, I'd start looking for another slow cooker before you make another batch. But the batch you made should be safe and fine to consume, assuming it's been handled properly otherwise!