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.it is unlikely for this to be related to the new key.
the key is recognized by the immobilizer which then signals the engine computer to allow start. The chances of a new key working fine, then somehow causing an issue after a few starts would be remote, although feasible I suppose. I have never seen this failure pattern, however, and think it is very unlikley. A bmw scan tool would be required to verify
I would suspect the issue is with the starter most likely, although there are a lot of things that can cause this type of no start. I would try unhooking the car battery for an hour, locking/unlocking mechanically a few times, checking all fuses and also trying a jump start.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.