[Alex323Ci]

we drove the next day about 100 miles and the car overheated - steam billowing out of the hood. The bleeder screw was a bit mangled and steam was pouring out.

sounds like the bleeder screw which is plastic either broke or was leaking. causing the system to not be pressurized and poor steam from it.
you can just replace the plastic bleeder screw. you can even buy some made if brass. less prone to heat brittling. but you don’t know yet if the top hose was cross treaded. so perhaps a new top hose is warranted.
good chance you’re fine

 

[Alex323Ci]

I replaced the entire upper hose. The threaded opening was pretty melted by the escaping steam. Works perfectly now.

nice to hear 👍🏻
if you did it yourself make sure the connections are tight between hoses, use only bmw hoses for best fit, bleed properly and keep a good eye on the temp for a few drive cycles.