Defect Phenomenon
Samsung Galaxy S8 Plus Cannot Boot
Troubleshooting
Disassemble the phone, connected with DC power supply with 400mA current leakage.
Keep powering for 10S, the touch with finger to feel the heat area, it located on the charging IC (IF PMIC).
Then we measure the chip related rail, find the main power supply for it get shorted.
Use rosin inspection method to find out the defective component. Apply 2A power on the main power supply rail. Find the rosin on a capacitor get melted. Then get it removed.
As battery current leakage, the battery get drained already.
Apply a 3.7V voltage to get the battery activated, then the phone can boot normally.
But when enter into the system, pop-up the thermometer symbol.
Get the wireless charging coil, the symbol still not disappear.
So the issue might be related with the thermal resistor. Check the thermal resistor on the wireless charging coil first, after removing the glue covered on the thermal resistor, we find it get cracked already.
As there’s no specification for this thermal resistor, we tried to replaced a 10K resistor, the issue still the same. Then tried 1K, 3.3K resistor to test, the issue is also unresolved.
Search the related signal WPC_THM, searching result as below.
So issue might be caused by the thermal resistor R7027. Maybe the resistant value with problem.
We can get it replaced with a new one with the same specification.
Searched another thermal resistor related with ‘CHG_THM’ signal, the specification of this resistor is 100K. So we can try to find a 100K resistor to get it replaced.
After replacing the resistor, ‘thermometer symbol’ issue get resolved perfectly.