2008 Mazda Mazda6 - Transmission is stuck

Transmission stick in Thiers fera

I am guessing you mean the shifter is stuck. if so this might help.
Mazda Shifter Stuck in Park | Manual Override | Won’t Go In Gear (youcanic.com)

What is a Thiers fera??

What type of transmission?

Does it behave differently when the engine is running vs not running? Manual vs automatic?