I have an electrical drain on my 2004 R53 coming from somewhere and I suspect it's the GPS as it stopped working around the same time. Does anyone know the fuse box code for the GPS? Please and thank you!

 

I'd suggest getting a multimeter to help possibly determine if/what circuit may be using up the battery while the vehicle is not running. Also, check your grounds and make sure there are good connections. If you don't have a multimeter we have some here. Some info here with advice you can possibly use to help diag what your issue is.