How to get working Player 2 Controller in this Homemade Arcade?

[Edgar Montes de Oca]

I don't know how to upload images so here is a link to download the images: https://www.mediafire.com/file/kejdse6up95l3zl/Arcade+Image.rar/file

This is a Homemade Arcade that my brother bought a time ago, they gave it to my sister recently. The coins Slot Machine doesn't work but I don't care that we can use a keyboard and that fixes the problem.

But we need the Player 2 Buttons and Joystick, they don´t do anything and this is the information I have:

-They worked before by pressing the top button at the back of the machine (Photo) but I took the cables out cause it was sometimes that it worked, so they connected the right way to the USB Interface cause I tested it when they were working.

-The entire machine power on when connected to the electricity without doing any extra steps.

-Is a Homemade machine with a Windows-based computer as a core, bad quality and slow but works perfectly with the arcade games.

-I cannot go to settings cause the startup is blocked, even with a keyboard and mouse I cannot do anything, a format method would be appreciated.

This button was to activate it or connect it to the power source?

What can I do or connect to make it work permanently without pressing the back button?

What core hardware I can buy to connect those buttons and joysticks that are small, faster, and cheap for N64 and PS1 games?