I'll also add the photos to show the way I installed this mod so that there was no damage made to the ribbon cables or LEDs. Everything lights up correctly and still and looks great!
I've upped my star rating from 3 to 4 now since these guys were fantastic to deal with and everything is now working correctly.
All things considered it's a relatively easy installation if you have already done a shell swap as you would have an idea of what goes where and how it connects to one another. The left joy con was definitely easier to do than the right one.
The only 2 issues I encountered were in the right joy con. The alignment of one of the R trigger LEDs is a tiny bit off and so it actually gets damaged when hitting the trigger. The positioning of the rest of the piece is in the correct spot, it's just this one LED that is misaligned. And the other was near the end of the install for the ZR trigger button.
The ZR area has a set of 3 LEDs that have to stick to where the battery pack is and go around a corner. I found that the double sided tape wasn't sticky enough even after pressing down with the plastic yellow tool multiple times to get it to stick. This resulted in it getting caught when closing the joy con back up which resulted in a damaged LED. While this happened all of the other LEDs still worked correctly.
A word of warning would be to make sure you are happy with the clickiness of the trigger buttons before closing the joy con back up. It seems the right joy con LEDs are permanently damaged now after trying to fix the trigger clickiness and closing the joy con back up due the the tape not making the LEDs stick down, unfortunately I had no double sided tape handy to try and add some to make it flush with the battery pack area, it seems this part not staying down and becoming damaged has ruined the whole piece of the mod.
I am unsure if I would classify the mod in the right joy con as faulty due to these two issues, as I believe the R trigger area is going to be damaged no matter what as the alignment is slightly off while the ZR trigger area would have been fine if the double sided tape was better and actually stuck to the battery pack area.
I have found that the damage to the mod shows itself by turning the LEDs green or flashing green when pressing certain buttons. When trying to turn the mod on using the SL and SR buttons this results in only the connectivity lights flashing. So the power is still working correctly just not the LEDs.
The joy con itself still works as it did originally it's just this mod doesn't in the right joy con due to being irreversibly damaged. I have removed the mod from the right joy con on the off chance that leaving it in will damage the joy con in some way as I imagine it could potentially short circuit the joy con due the power from the battery pack going through the damaged mod.
After thinking it over more, I've changed my review from 4 stars to 3 as this was a $53 (AUD) purchase and it needs improvements to be made to the right joy con mod layout. If it wasn't so much it would be more forgivable but considering it's half the cost of a brand new set of joy cons it's a little dissapointing. The other reason I'm leaving it as 3 stars is because the left joy con has had absolutely no issues in installation or during use.