Get your Micro Player from My Arcade or Amazon. For this instruction I used the Galaga version but any version will do: https://www.myarcadegaming.com/collections/mini-arcades/products/galaga-micro-player
Step 1: Open the Case
a. Remove the 4 Phillips head screws from the back af the case (highlighted in red).
b. Use a flathead screwdriver and 2cm from the top insert between the side and the case and pry open (highlighted in red).
c. Repeat at the bottom (also 2cm from the bottom of the case).
You could also remove the large Galaga sticker that is glued to the sides, but prying it open worked just fine for me. The stickers themselves are of quite good quality and use thick paper. So you can remove them to expose the screws and glue them back. The adhesive is good enough that it can withstand 1 or 2 removals and reapplications without needing new/extra glue.
As you can see from the 3rd picture every side is tied down with 5 screws. We only need to remove/bypass the red highlighted ones. The amber highlighted ones hold down the rest of the case.
Step 2: Remove the Main Circuitboard
d. remove the 4 small Phillips head screws (highlighted in red) to get access to the main circuitboard*.
*Note: when you remove the main circuitboard the screen that is attached with a ribboncable will also come loose.
In yellow you can see the small pesky screws that tie the sides to the main case. I decided to remove all the electronics from this machine (for another project) so you can see that how the screen is attached via a ribbon-cable to circuitboard and folded over in the case itself.
Step 3: Expose the Circuitboard
e. remove the black foam from the circuit-board (highlighted in red).
The black foam is used to rest the display on when it screwed in place and of isolates this from the main circuitboard. So when reassembling make sure to re-attach the foam.
Step 4: Acces All the Other Games....
f. By shorting the IOB1, IOB2 and/or IOB3 we get access to the other games.
IOB1 -> DigDug
IOB3 -> Galaga (the one that was enabled by default on my model. Of course).
IOB2 -> Mappy
None -> Rolling Thunder
In fact, any combination of two or more IOBx will also give you Rolling Thunder. So the only step now is to decide what to do with these additional games... The easiest I think is adding a simple dip switch and you are done. 4 games for the price of 1!!!