1. Turn your Sony VGNCR309ERC laptop over.
2. Find the laptop battery release button lock for your Sony VGNCR309ERC laptop.
3. Now that your Sony VGNCR309ERC laptop battery is unlocked, find the battery release button down.
4. Holding the laptop battery release button, gently pull your battery away from the laptop.
5. Now that your Sony VGNCR309ERC battery is removed, grab your replacement Sony VGNCR309ERC battery for installation.
6. Insert the battery into the slot. Push the Sony VGNCR309ERC battery towards the laptop and secure it in place.