Here is the pre-configured Retropie image and wiring diagram from my PlayStation Classic project. Whether you decide to cut the PlayStation Classic board, create a new board, or hot glue everything in place this will help you achieve a nice installation with working buttons.
5V on the GPIO is only necessary if you are planning to hard-wire the power connection.
The power button triggers a safe-shutdown script so you don’t have to worry about SD card corruption when powering down.
The Reset and Open buttons are both attached to two pins each.
Download Retropie Image : https://drive.google.com/open?id=11e8w6pszSSV0V2FuAtm35rbN-dyduUAI
When you boot the SD card for the first time it may go to a black screen after the PlayStation splash screen. If this happens wait about 30-60 seconds and pull the power from the Pi. After that it should boot fine.
Once you get the system running, make sure to expand the files system to ensure that you have all the space on your SD card available to you. To do this run Raspi-Config from the RetroPie options menu, select ‘Advanced Options’ and choose ‘Expand File System’. Reboot when prompted and you should be good to start adding games!