This tester is used for test signals of motherboard check the open circuit short circuit of BGA and CPU socket etc. Instead of traditional complex testing methods it can test every pin accurately. - When changing the BGA Bridge it can determine the connection of BGA through the LED on the board. - Connect a CR2032 3.2V battery to the CPU tester and plug to the CPU Socket of the motherboard - Press the switch on the upper right corner of the tester if some LEDs are not lighting you can check the open circuit and short circuit of BGA and CPU socket. If some LEDs are brighter than others please check whether the LED is short circuit. - Connect the motherboard power supply check the CLK and RESET # VCCA by oscilloscope