I'm currently trying to fix my headphones with a TRRS jack that I recently purchased. I'm using my multimeter and have figured out that green/blue wires together make up the left audio channel and red/black make up the right audio channel. How would I wire this? It seems that there are two grounds but I don't know which is which. Thank you in advance.
Why did you buy a Tip, Ring, Ring, Sleeve? Almost all stereo jacks are Tip, Ring, Sleeve. Look here for more info.
To do this properly you would need to do a conductivity test of the old phone jack to the different colored wires. If that is not possible it is likely you can twist 1 wire from each side together and connect that to the sleeve. Then connect the remaining 2 wires (independently) to tip and ring. If by chance it works, you have a 50% chance the phase will be correct. And a 50% chance the left channel is on the left and the right channel is on the right.