No, LED is not illuminated.
I tried with different power supply (not the same model of NUC), LED is not illuminated.
I will try with the same model of power supply tomorrow but i think something is wrong.
Be aware that the Standby LED has low light intensity. Please verify that in dark environment you can't see light illumination on the board bottom side (just below the front blue USB port).
Verify also that you have power in the wall receptacle. And yes, try to use other Power Supply Adapter.
If still your NUC will not power ON, probably the Power Input Circuit failed and you need open request to RMA in order to replace your NUC under warranty: https://supporttickets.intel.com/warrantyinfo?lang=en-US
We found another support ticket where you describe the same issue reported on this thread. It seems that the unit was replaced and the new unit is up and running.
If you need further assistance, please let us know.
Intel Customer Support Technician
A Contingent Worker at Intel