Xiaomi 10 Cannot Boot Caused By Continuous Dropping Damage
Model: Xiaomi 10
Announced: 2020, February 13
Defect Phenomenon
The kid plays with the cell phone as a toy, after keep dropping it several times the phone screen turned to black and cannot boot.
Troubleshooting
Place the cellphone on the heating pad to heat and separate.
After seprating, we find the phone has not been repaired yet
Then remove the wireless charging coil and all the screws, then measure the voltage value on the battery.
The battery voltage is normal
Then buckle the battery and test again, the phone still cannot be booted.
Then let’s check the motherboard
First, let’s solder a wire for the positive DC power input connection
Then connect with the DC power supply and trigger to boot
The boot current is 50mA only then drop to 0
Based on the repair experience, this kind of defect normally is caused by CPU poor soldering or the CPU relative buck voltage inductor poor soldering.
Repair Process
Let’s start from the simple part, to check if there’s any poor soldering inductor.
Push the inductor around the PMIC with tweezers slightly, find there’s no loose inductor.
Then let’s remove the shielding cover on the power supply chips, well keep the removed shielding cover, as we will need to solder them back after repairing is done.
Carefully check the components under the shielding cover again, everything is OK.
Then the next step, we should resolder the CPU chip to have a try, we should also remove the shielding cover first.
Let’s remove the upper layer of the CPU chip first
After that, remove the lower layer of the CPU
After removing the CPU, we can start to clean the pads on the PCB.
Tips: Xiaomi Mi10’s CPU is not sealed with glue, so the pad cleaning is much easier, we just need to use the solder wick to remove and flat the tin pads.
It’s convenient for repair, but the CPU without glue sealing is not very stable, and the heat consumption effect is poorer.
OK, let’s continue to reball the two layers of the CPU.
After resoldering, step by step, let’s resolder the two layers of the CPU to the motherboard.
The CPU resolder is finished
Assemble the phone temporarily to have a test, the phone can be booted normally.
Last but not least, let’s solder back the shielding cover, then assemble to test again to ensure all the functions are OK.
The phone can boot normally, and all the functions are tested OK after assembling.
