Received a SAMSUNG note 9 cannot turn on, the phone stopped working during normal use.

● SAMSUNG Galaxy S9

   Released 2018, August 24 

The client took the phone to the official after-sale center to repair it. And the diagnosed result is the motherboard problem, need to replace the motherboard with a new one. Since the phone was out of warranty, the cost of repair is quite expensive. So the client brought the phone to our repair shop.

Repair Process

● First, try to press the power button to restart, and change the new charging cable as well as a new battery to test, but the issue is still unresolved.

● Then disassemble the phone to check the motherboard, the cosmetic of the motherboard also looks good, with no obvious water or drop damage, no corrosion, or part missing.

● Check the motherboard with supply with the multimeter, it’s found the motherboard main power supply rail shorted to ground.

After that, measure the main components relative to the main power supply and find it’s a filter type capacitor near the Wi-Fi chip get shorted. 

As we learned in the before repair cases, the shorted filter-type capacitors normally can be ticked off directly.

So in this case we can also just tear it off directly.

(Remove directly to avoid the damage by hot air gun soldering)

After that, measure the diode value again, it’s back to normal.

Since the cannot boot issue is caused by the main power supply shorted to the ground, the original battery has been exhausted and need to be activated by the activation board for the mobile phone battery.

After the battery gets activated, then assemble the phone to test. The phone can start up normally and all the functions are OK. 

Summary

The cannot turn on issue is caused by the filter type capacitor near the Wi-Fi module getting shorted, issue gets fixed by removing the capacitor directly and then activating the battery.