Motorola G8 Power Lite Dead Phone Repair – Step by Step Diagnosis Guide

In this tutorial we will learn how to diagnose a dead smartphone using a smart charger and DC power supply. Today’s repair case is a Motorola G8 Power Lite which is completely dead and not turning on.

Device Condition: The phone is completely fresh and has never been repaired before.

Step 1 – Checking Current on Smart Charger

First we connect the phone to a Smart Charger and observe the current consumption.

0.1A → 0.2A
0.6A → 0.5A
0.2A → 0.1A
Then current drops to zero

This type of behavior indicates a Low Boot Condition.

Step 2 – Testing with DC Power Supply

Next we connect the board to a DC Power Supply.

First we check whether the board has a short circuit. In this case there is no short circuit present.

When the power key is triggered, current rises from:

12mA → 26mA → 27mA

When the trigger is released, the current goes back to zero.

This confirms the phone is in a Low Boot State but not shorted.

Step 3 – Board Inspection

After disassembling the phone we identify the major components:

MediaTek CPU
24 Pin Charging IC
MT6357 CRV Power Management IC
Five Buck Coils near PMIC

Step 4 – Checking Buck Voltages

The power IC generates multiple voltages through buck converters.

High LDO → around 2.05V
Other Buck Lines → 0.6V – 1.2V

These voltages must remain stable.

In this case the voltages are present but continuously fluctuating, which prevents the phone from booting.

Step 5 – Capacitor Short Check

Next we check the capacitors around the power IC using a multimeter in diode mode.

If any capacitor shows 0 reading, it indicates a short circuit.

After checking multiple capacitors, no short circuit was found.

Step 6 – Checking Boot Sequence

According to the MT6357 Boot Sequence, the power IC first generates:

VREF
VDIG
VRTC
VXO
VAUX

After these voltages stabilize, the buck converters start operating.

Step 7 – Checking RESET_B Signal

RESET_B is generated by the power IC and sent to the CPU.

If RESET_B is missing → PMIC fault
If RESET_B fluctuates → CPU issue

When measured, RESET_B shows 1.8V but fluctuating.

This indicates the CPU cannot hold the boot sequence properly.

Step 8 – CPU Reballing

Based on the diagnosis, we proceed with CPU Reballing.

CPU removed using hot air station
Board cleaned using flux and solder wick
CPU cleaned and reballed with stencil
CPU installed again on motherboard

Final Result

After reinstalling the CPU and assembling the phone, the device successfully powers on.

Conclusion: Proper diagnosis using voltage checks and boot sequence analysis is very important before replacing components.