Based on my experience with starter failure/replacement in the X3, it will be intermittent before completely failing.
My ZHP’s starter is in the intermittent phase, but I have a new one on the shelf for whenever I feel like doing it. About 1 in 5 times it will spin up, but not engage. I then take the key out, put it back in, and it starts on attempt #2 every single time. Thus, I think my solenoid is not pushing the starter motor wheel thing (yes that’s the proper term) onto the crank, so it’s just free-spinning in place. I probably am not typing that coherently, but it makes sense to me