Your potential issues are way past my pay grade, with repairs being done and then slowly fading back to an on/off no start.
However, consider cross posting, your post (copy/paste) to:
https://www.z4-forum.com/forum/index.php This is a mainly a UK Z4 forum. I can recall posting there that involved no starts which required the EWS delete. Cross posting there should double your odds of finding your answer.