Thank you for this advice.
Unfortunately, I've encountered a new physical problem. Software appears to be 100% fine.
After doing the joycon faceplate change, the LEFT joycon does not charge--at least, that's the theory.
It worked fine for a day or so.
Now it doesn't connect to the switch at all. It doesn't respond to being "clicked" in, nor does it register when trying to pair. It worked once during troubleshooting and responded to the "click", but as soon as the joycon was removed, it stopped again.
When the pairing button is pushed, the pairing light will come on intermittently. It does not connect to the switch. The intermittent part may possibly related to the ZL button being slightly pressed down? Sometimes (once out of 100 times), by fiddling with the ZL button, the pairing light came on.
The switch works with other controllers so it doesn't appear to be an issue on the switch side.
I doublechecked the orientation of the battery and does not appear to be the issue.
Here are pics of the current joycon repair in progress--if this isn't the thread for this, I'll gladly remove and go there. Thanks in advance!
In pic "BATTERY", you can see this connector doesn't seem to be clipping very well, but it's still intact and holds the ribbon.