This guide will walk you through the process of transferring the board from the OEM Subaru Key Fob to the Miniature Key Fob.
STEP 1: Separating the OEM Fob Halves
Depress the square silver button on the back of the fob with your fingernail while simultaneously pulling on the key ring at the bottom. This will release the physical key from the fob. Only pull the key out about halfway.
While firmly grasping the metal sides of the fob in one hand, use the physical key as a lever by pulling straight down. This will separate the two halves of the fob.
The top half of the fob (with the silver trim) can be set aside, along with the button layer, and the rubber waterproofing gasket. Remove and set aside the physical key.
STEP 2: Removing and Separating the Board and Battery
Flip the bottom half of the fob upside down to dump out the board/battery combo. You can then set aside the bottom half of the fob.
Look at board closely. Note that it is held in place by six little black plastic tabs. Carefully manipulate those tabs to pop the board off of the plastic chassis. Use your fingernails (and you can also flex the plastic chassis a tiny bit) but be careful not to break anything. Once you get enough tabs free, the board should pop off easily. Set the board aside for a moment.
Flip the chassis over to access the battery. It too is held in place by some clips. The easiest way to remove it is to simply grab one of the bottom corners of the plastic chassis, and flex it down. The battery should pop out and can be removed. Set the chassis aside.
STEP 3: Assembling the Mini Key Fob
Place the battery into the lower half of the Mini Key Fob. Make sure it's oriented properly; it should be face down, with all the writing on the bottom (positive side down!) Basically, the shiny, flat side down, and the rounded, rough side up.
Now comes the most complicated part of the install. Pick up the board. Note the side with the four buttons, which you want facing up, obviously. Look at the bottom and you will notice a pair of springs where the battery sits. There is a spring that contacts the top of the battery, and another curved spring sitting perpendicular to the board which contacts the side of the battery. Because of this curved spring, you cannot simply place the board straight down into the fob chassis. Instead, lay it down with a 1-2 mm gap to the bottom. Then, while holding the bottom in place with your left thumb, gently slide it into place, and press down with your right thumb to ensure it seats into place. The board should sit flush with the rim of the fob chassis all the way around.
Retrieve the physical key you set aside earlier, and remove the small ring loop. Then insert it into the curved slot on the top half of the fob. Note make sure it is fully inserted and sits flush. Be gentle handling the top half of the fob through the following steps to ensure it doesn't fall out until fully assembled.
Now take the two halves, and slot them together on the top side. Then place the fob down on a flat surface and firmly snap the bottom sides together. This can take some force.
STEP 4: Systems Check!
Make sure and test the four buttons to ensure you can feel them click. This ensures something didn't go wrong with the assembly, and that your board is compatible. You should be able to press the buttons, but it shouldn't be OVERLY easy to accidentally press them.
If you ever need to separate the two halves again, carefully slide a thin, wide object (such as a butter knife) into the horizontal gap just underneath the key ring at the bottom, and then carefully twist back and forth until the two halves snap apart.
Enjoy all that extra space in your pockets!