If it's secured anything like the E46, there are retainers that you press into the dashboard, and the trim clips into the retainers. If the trim was ever removed the retainers may be damaged or loose. Happened on my E46 and I replaced a half dozen of them.
The only tricky part is manoeuvring the Start button and pulling the trim piece, but you should look for DIYs on this. Once you have the Start button and the trim out, replace the loose retainers on the dashboard and put everything back. You shouldn't need any special tools except for the trim removal tool (which you can substitute by bandaging insulation tape over a slim flat blade screwdriver). The retainers themselves are inexpensive, about a buck a piece tops.