Pulsar X2 v2 Medium mouse battery replacement

I wanted to put out a more complete guide than what's currently available for people who may want to do this in the future; welcome to my blog.

Love the mouse, but the battery wasn't lasting more than 3 days.

Here's a pic of the original battery (602030 300mAh 3.7V):
https://drive.proton.me/urls/TT7GVDNG5C#BKMx0MHmSwvg

I bought a replacement battery from AliExpress:
902030 550mAh 3.7V JST 1.5mm 3pin

Here's a pic of the final result:
https://drive.proton.me/urls/BEMDHJH668#I2ZixElmwv7E

There's plenty of height clearance, but no wiggle room with length and width.

The most important tidbit is the polarity of the wires; I had to swap red(+) and black(-).

On the original battery (all black wires) you can see the P- and P+ indicators on the original battery (PCB). What this means is the "bottom" of the connector (on the mouse) expects a positive (red wire), middle is the sensor (yellow wire), top is negative (black wire).

The battery arrived with the red and black wires the other way around. I used the smallest flathead screwdriver to, very slightly, prop the plastic "prong" (where you see the three plastic 'prongs', not the flat side) of the red/black wire and gently pull them out. Take note of the wire's positioning (the metal bit). The top has a very tiny metal bump that "clips" against the plastic prong you lifted. Putting the wire back into the housing should be "like a glove"; no forcing.

Everything is working without issues so far. The Pulsar software is reporting the battery level, but can't be sure if it's accurate. I also haven't had a chance to measure how long the new and improved battery lasts.