if you don't have Idrive the reset process is pretty confusing...that might be where your problem is.
turn your car on and use the BC button to go to the tire pressure option.
hit the BC once and then press and hold it until you get the actual reset dialog on your dash.
I spent weeks frustrated from the warning light and manually checking the tires until I figured this out
Current Mods: JB4 , H&R Rear Sway bar, Front Strut Bar , 19" M5 Reps Staggered , NBT retrofit , JBL MS8 Amp and 10" Sub, 6WA retrofit