When the current of motherboard is abnormal, it often leads to boot failure. In the video we fix a Samsung S9 in such conduction. First we tear down the phone and take out the motherboard. Then we check and test motherboard and find that its current is abnormal, a resistor has been missing and an IC is out of tin. Therefor we replace a new resistor and coat new tin on the IC. This Samsung S9 has been fixed completely.