Case Study: Samsung Galaxy A16 Powers On but Won't Charge — A Motherboard-Level Repair

A phone that won't charge doesn't always have a damaged charging port. Sometimes the charging port is perfectly fine. The charging sub-board works. The cable works. The battery may even be healthy.

The real problem can be hidden much deeper inside the phone's motherboard.

Recently, a Samsung Galaxy A16 was brought to Watz Electronix with exactly this type of fault. The phone powered on normally and worked perfectly from its remaining battery charge, but the moment a USB-C charger was connected, absolutely nothing happened.

What initially looked like a simple charging problem turned out to require component-level motherboard diagnostics and precision micro-soldering.

The Samsung Galaxy A16 arrived at our workshop with the following clear symptoms:

At this point, continuing to replace external modular parts blindly would not solve the problem. The fault had to be traced through schematic line analysis.

A modern smartphone does not send power directly from the USB-C port into the battery cell. Instead, charging voltage travels through several sophisticated stages before reaching the battery management system:

USB-C Port → Charging Sub-Board → FPC Interconnect Cable → Main Motherboard → Protection Circuit (OVP) → Charging IC / PMIC → Battery Terminal

The first step was to determine exactly where the 5V charging rail was disappearing.

We began by measuring whether incoming 5V VBUS voltage from the charger was successfully reaching the main logic board.

The incoming line measured approximately 5.1V at the motherboard FPC connector test pads. This confirmed key facts:

This was a critical benchmark: the problem was definitely not at the charging port or bottom flex.

Next, our technicians traced the 5V line through the Over-Voltage Protection (OVP) IC and onto the main charging input rail.

Voltage was successfully passing through the OVP protection MOSFET and arriving at the filtering capacitors surrounding the phone's dedicated Charging IC / PMIC.

We also conducted diode mode and resistance-to-ground measurements across all surrounding decoupling capacitors on the input rail. There was no direct short circuit to ground.

So we now had a very specific, isolated scenario: Charging voltage was entering the motherboard correctly, yet the charging system remained completely inert.

Attention shifted directly to the charging IC itself. The charging IC manages incoming electrical power, negotiates handshake protocols, and controls how energy is stepped down and delivered to the battery cell and system power rails (VSYS).

Using high-precision multimeter probe measurements and live voltage checks, we analyzed the IC's buck converter coil output and I2C communication lines.

Although 5V input voltage reached the IC input balls, the expected switching frequency and output charging current were missing. The device was receiving power, but the silicon chip was incapable of processing or routing it.

This definitively isolated the fault to internal failure inside the charging IC component.

Once the fault was isolated, we proceeded to replace the defective charging IC. Unlike modular parts swapping, motherboard micro-soldering requires precision thermal profiles and microscope navigation:

1. Preparing the Motherboard: The logic board was clamped securely in a precision PCB fixture. Heat-resistant polyimide (Kapton) tape and thermal shielding were applied to safeguard adjacent CPUs, memory chips, and plastic connectors.

2. Removing the Faulty IC: Using a calibrated hot-air rework station at 340°C with controlled airflow and premium no-clean tacky flux, the defective BGA charging IC was desoldered and lifted cleanly without pulling any board pads.

3. Cleaning and Preparing the PCB Pads: Residual oxidized lead-free solder was removed from the PCB pads using copper desoldering braid and micro-soldering iron tips. The area was ultrasonic-cleaned and checked under 45x magnification to ensure zero solder bridging.

4. Installing the Replacement IC: A brand-new OEM charging IC was precision-aligned over the pad grid, followed by controlled infrared/hot-air reflow. Surface tension snapped the IC into perfect alignment.

After allowing the motherboard to cool down, the device was reassembled and connected to a USB power monitor.

The response was instantaneous:

The Samsung Galaxy A16 was fully restored to factory charging performance without needing an expensive full motherboard replacement.

Whether your Samsung Galaxy A16 has broken front glass, refuses to charge, or shuts down prematurely, Watz Electronix provides rapid same-day bench services across all 4 workshops in Nairobi and Kiambu:

Visit any of our convenient walk-in workshops at Roysambu (Lumumba Drive), Kasarani Arcade, Kahawa Wendani, or Ruiru (CNM Centre) for instant repair service.