I'd also like to use my Note 4 as a desk clock. The Samsung clear-window flip cover brings up the desk-clock mode behind the window when the flap is closed, handy feature, but it doesn't stay on when you have the phone plugged in. I went to the Developer Options, and checked "stay awake while charging," but the problem with that, is after the phone is charged, it shuts off. Not like the Note 2, which didn't shut off when it was plugged in either in my car, at my desk or on my nightstand.
If anyone knows how to fix this, please do tell.
Thanks