Nintendo Switch Lite ZL not responding

So the ZL button on my son’s switch lite has stopped working. I have opened it up and cleaned out the button contacts with alcohol to make sure no dust or debris was in the way. I have pulled the ‘left’ control board to see if there was any noticeable damage and cannot find any visually. I’ve reseated the ribbon cables and cleaned out any ‘gunk’ I found again with alc. I’ve also switched the button ‘pad’ from the ZR that makes contact with the board to the ZL and still nothing is working. I am about to just order a replacement left board because I can’t think of anything else that would case this to stop registering. Everything else works flawlessly on the device outside this one button. What can else could cause this?