If the selector lever will not move from P using the proper shift procedure, continue to hold down the brake pedal.
1. Remove the shift-lock override cover using a cloth-wrapped flat head screwdriver.
2. Insert a screwdriver and push it down.

3. Press and hold the lock-release button.
4. Move the selector lever.
Take the vehicle to an Authorized Mazda Dealer to have the system checked.
Shift-Lock System
Transaxle RangesMazda 6 Owners Manual: Clutch master cylinder disassembly/assembly
1. Disassemble in the order indicated in the table.
2. Assemble in the reverse order of disassembly.
Snap Ring Disassembly/Assembly Note
Hold the piston down using a cloth-wrapped pin punch.
If disassembling, remove the snap ring; if assembling, install it.
...
Mazda 6 Owners Manual: Timing chain
TIMING CHAIN REMOVAL/INSTALLATION
Warning
Fuel vapor is hazardous. It can very easily ignite, causing
serious injury and damage. Always keep sparks and flames away from fuel.
Fuel line spills and leakage are dangerous. Fuel can ignite and
cause serious injures or death and damage. Fuel ...