I just had a dash rattle fixed with no problem by my local BMW i dealer - Arden BMW in Maidstone. So I don't know why anyone would mess with the car themselves while it is under warranty ?
The rattle came from the glove compartment, and was noticeable when driving over slightly bumpy roads. It stopped when opening the glove compartment.
The service department found the source quickly, it turned out two panels behind the glove compartment were rubbing/ bumping against each other. They inserted some felt in between and the noise stopped.
It shouldn't happen but the service was top notch - picked up from work, kept me informed throughout the day on progress, and took the car back, cleaned and fixed.
BMW i3 BEV - ordered 18th Dec 2014, at dealer 26th Feb 2015, delivered 16th Mar 2015.
Spec: Ionic Silver, Suite, Harman Kardon, Driving Assistant Plus, Media BMW Professional, 19" 428 Alloys, DC Rapid Charge Prep, Park Assist.