How to diagnose Samsung Galaxy A40 Charging Problems

Locate the +5V power line running from the charging port to the motherboard.

Heating to high temperatures can damage sensitive components — use caution.

• Apply heat to soften the adhesive using a gentle heat source or isopropyl alcohol.
• Use a suction cup or a thin, flexible tool such as a playing card to assist removal.
• Remove the silver Phillips screws from the device's frame using a screwdriver.

• Remove the plastic cap from the fingerprint flex cable connector.
• Disconnect the cable.
• Remove the SIM Tray.

Remove the back cover starting at the SIM tray hole using a plastic tool.

• Do not touch any electronic components to avoid damage.

• Disconnect the battery connector.

Disconnect the main flex cable.

• Connect the charger and use a multimeter to measure voltages at the large end pins of the FPC connector on the charging board.
• If the reading is ~5V, proceed to the next step; otherwise, replace the Charging board.

If faulty, incorrect voltage readings may indicate a damaged Charging board.

• Attach the main flex cable and measure voltages at the large end pins of the Main flex FPC connector (pic.3).
• If the reading is ~5V, proceed to the next step; otherwise, replace the Main flex cable.

Remove the adhesive rubber from around the main flex connector.

• Apply solder paste or flux to the affected area.
• Use a soldering iron to re-solder the first pin of the motherboard FPC.