Rigging NES On/Off Board to a Raspberry Pi or other

[PunkHaz4rd]

Hello, first time poster here.
I'm currently trying to build a versatile media center inside my original NES case to launch whatever SSD equipped NES Catridge I have. That part seems fairly easy to me. The modification of the circuitry on the other hand is [almost] completely unknown to me. I know how to weld but recognizing what goes where is really hard.

You can look at what I'm talking about on this imgur link.
Cables:
1- Brown
2- Red
3- Orange
4- Yellow
5- White

I want to keep the board as is, but cut the cords and weld them on a raspberry pi or others to:
- Power on the machine
- Have the led from the board indicate when it's on instead of the one on the board
- Find a function for the 'Reset' button

My questions are:
- How can I determine which cable correspond to what ?
- If I make a association mistake and test it powering on, can I damage the components I'm working on ?

Thanks

EDIT: I figured this isn't really an assignment, but I also want to learn how to figure it to be able to replace it in case something stop working in the future.

 

[Martaine2005]

A simple continuity tester or mutimeter is required.
Check continuity of each wire to each switch position.

Martin