The side buttons are located here, on a small and delicate ribbon cable that wraps around from the left side of the frame to the inside, under the motherboard.

Insert the tip of your tweezers under the contact pads. There is a small gap that is hard to see that will let you get your tweezers under the contact pads to provide some leverage.

Once the contact pads are lifted up, gently pull the ribbon cable up with your fingers to release it from the adhesive holding it to the frame.

Stop pulling once you've gotten to the side of the phone. You can not yet completely remove this ribbon cable.

It is important that you do not insert your tweezers anywhere not recommended by this guide. Only remove the ribbon cable by gently pulling the adhesive off. Only these three spots have a metal backing that will protect the ribbon cable. Anywhere else can cut or otherwise damage the ribbon cable.