First, make sure that the power cord is securely plugged into both the terminal and the wall. If there is a surge protector between the terminal and the wall, make sure it is connected firmly as well. Finally, note that the power cord is made up of two pieces that connect in the middle. Make sure all of these pieces are firmly connected as well.
If the problem persists, try plugging the terminal into another outlet or surge protector.
If you are a 360 Payments customer and this still doesn't solve the problem, call us at 408-295-8360.