They say a picture is worth a thousand words, but since I can’t post media yet, I’ll have to try with words.
If you are looking at the motherboard with Side-B text right side up, it’s on the far left side to the right and down from the UM circle and to the immediate left of the top left corner of the eMMC. It’s a grey rectangle. There is a yellow triangle pointing right that is up and to the left of the component.
It has come off due to liquid damage and is possibly also corroded beyond use. What is this component and can it be bypassed or fixed in some way to run the Switch Lite long enough to transfer an Animal Crossing island?