If you are going to do very much work on the Car you would be well advised to purchase The M car manual from Helm for the vehicle it gives pinouts, schematics, instructions on how to remove the panels and which panels to remove to get to the components.
That being said! and with the understanding that I claim no responsibility if you take your car apart and break something or short something out
On the Left side of the vehicle the Insulator panel (panel farthest underneath the dash is removed first (3 push in fastners) Then the Knee bolster (panel immediately below the steering wheel )(Four screws two on side and two on bottom)
On the Right side of the vehicle the compartment door comes off first (two hinge pins and a retractable cable) Then The compartment frame Two screws on outer side,two screws on top underneath bolt caps 1 at top of door opening and two on bottom.
Next the trim panel where the seatbelt notification is at needs to be removed (Snaps in)Then the lower instrument trim panel(panel around the radio 1 Screw and six push clips. after that four bolts two on each side of the radio and it should come out in your hands
Be gentle and Good Luck!