Now looking at the PCB on it's own, Take note of the 4 Solder Terminals marked on the second image of this step.

The two terminals circled in Red are the Battery terminals. These terminals compose of the positive and negative pins attached to the battery on the other side of the PCB. The positive terminal is the one higher on the board in this image, while the negative terminal is the one below the first.

The two terminals circled in Green are the Resistor terminals. The two terminals are the ends of two resistors seen on the other side of the PCB. Why are these important? Well, these terminals are what we will be connecting our Parity Battery to.

Why connect the Parity Battery to resistors you ask? Well there's logic behind this. Take note of the PCB around the two battery terminals on the first image of this step. If you're unaware of how circuit boards work, the lighter green areas of a PCB (visible in the image) indicate a copper lining under the solder mask.

This copper lining is the link between certain terminals on the PCB. In this case, you'll notice that there's copper lining on the board that links the positive batter terminal with the resistor terminal next to it. The negative terminal in the same respect. This is marked in the second image written in blue.

To confirm this, you can use your Multimeter to check the voltage of the battery on its two terminals (Red). if you check the two resistor terminals (Green) in the same way, you'll notice that it displays the same voltage as the battery terminals.

By attaching the Parity Battery to these resistor terminals, electricity will continue to run through the PCB and hold the sensitive data stored on the cartridges SRAM. Meaning that while you replace the Main battery on the PCB, the cartridges saves will not be deleted the moment that the board loses power.

KEEP IN MIND, that the positive end of the parity battery must connect on the positive circuit of the PCB. Parity is ONLY achieved if the positive and negative ends of the battery are connected to their respective circuits. If you connect the battery the other way around, you'll end up connecting your batteries in Series, which increases Voltage.