Why won't the LED turn off?
The LED on the drill won't shut off unless I completely remove the battery pack.
The button flush to the handle of the driver activates a timer which controls how long the LED will stay on. Before trying to repair your LED, wait over 20 seconds since it could be that the switch hasn't timed out yet. If the LED continues to glow, it might be time to replace the light button assembly. This means that the wiring and chip responsible for the timing of the light must be broken and you must replace the timing chip. This question and more can be answered on the RIDGID X4 18V Lithium-Ion Impact Driver Troubleshooting page.
I have the same problem but I have a modded controller with custom LEDs inside it and when I turn it off the red lights are glowing slightly and my actual LEDs are still on bright and still changing colour !! Please help as this controller is new !!