I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.
if the engine is running much worse than before and vibrating and making noise, then he definitely did something wrong. could be incorrect tightening of components, incorrect alignment, etc.
I would strongly advise that you have the car inspected immediately by a main dealer or BMW specialist as serious damage could result form further diriving in this condition
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.
yes that is possible
the only way to know 100% is to fix that issue and re test