If the selector lever will not move from P using the proper shift procedure, continue to hold down the brake pedal.

Take the vehicle to an Authorized Mazda Dealer to have the system checked.
Shift-Lock System
Manual Shift ModeRear Trailing Link Removal/Installation
CAUTION:
Performing the following procedures without first removing the ABS wheel-speed
sensor may possibly cause an open circuit in the wiring harness if it is pulled
by mistake. Before performing the following procedures, disconnect the ABS wheel-speed
sensor wiring harness connec ...
Air Intake Actuator Inspection [Full Auto Air Conditioner]
1. Connect battery positive voltage to air intake actuator terminal B (or C),
connect terminal C (or B) to ground, and then verify that the air intake actuator
operates as shown in the table.
If the operation condition is not normal, replace the air intake actuator.
...
Transaxle Oil Replacement [G35 M R]
1. Park the vehicle on level ground.
2. Remove the aerodynamic under cover No.2..
3. Remove the drain plug and washer.
4. Drain the oil into a suitable container.
5. Install a new washer and the drain plug.
Tightening torque
39—59 N·m {4.0—6.0 kgf·m, 29—43 ft·lbf}
6. Remo ...