The XPS 13 laptop has an LED board in it. The board plugs into the motherboard, but it's not really clear to me what's for. The board is pictured here, www.ebay.com/.../262105473513
It holds the system LEDs -- charging, power, etc. They're on the front edge of the palmrest in this model.
The LED board in the link provided on Dell XPS 13 L321X is Power button board cable.
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