If Note4 won’t power on…
Another thing to try:
-Worked on another Note4 with problem, and did work for me...
-Connect it to a FAST Charger (the one that comes with phone)
-Wait for 30 sec or so, then try again (unplug/plug-in), if it fails
(Should see a "Lightning Bolt" icon on the screen... then try to power on)
-Being a “power” problem, this can JERK it back into booting!
-If it gets HOT, then try switching over to a normal USB charger to continue charging