Unscrew the screw labeled 5.

Use a tool to remove solder from the contact with number 6.

The double stick tape on the left is distributed in from 1 to 4.

First gently remove the contacts of buttons 1 and 2 and take them off of the slot.

Then use a tool to gently take off the main board with number 3.

Note that there are also components on the back of the main board, so be careful not to break them.