The trigger assembly that connects the button to the motor can sometimes break. This guide will explain how to replace the trigger assembly.
In each of the four rectangular slots on the bottom of the device, there is an E-shaped clip.
Wedge the spudger between the flat side of the E-clip and the outside wall of the slot. Then, loosen up the clip by prying it inward with the spudger.
Work your way around the four clips, loosening each a little at a time. Eventually, all four clips will be loose enough to remove the base plate.
The trigger button is held in with light tension clips. Gently pry them back to release.
Remove the white trigger.
Desolder the contact points between the trigger button and the red wire and also where the plug attaches to the trigger button