When a smartphone stops taking energy from the network, it always takes you by surprise. Especially unpleasant if the Xiaomi Redmi 9 does not charge at a time of urgent need for a communication device, the problem can lie in both the banal contamination of the port and a serious hardware failure of the power controller.
Users often panic, believing that expensive motherboards have failed, but practice shows that in most cases, the cause lies in software errors or worn out consumables, and competent diagnosis will save time and money.
In this article, we will go into all possible crash scenarios, look at software resuscitation techniques and ways to test the hardware without opening the case, and carefully follow the instructions to bring the device back to life.
Primary diagnosis of external factors
Before looking for complex software bugs, you need to rule out the basic causes. Often, a USB cable has internal fractures of the veins that are not visible visually. Try connecting another cord to your smartphone, preferably original or certified.
Pay special attention to the power adapter. If you use a cheap power supply from the market, it can give unstable voltage. Xiaomi Redmi 9 is equipped with a protection system that blocks charging when current surges. Use a proven power source with a power supply of at least 10 watts.
⚠️ Warning: Using damaged cables with protruding wires may result in short circuit and final failure of the power controller.
It is also worth checking the charging connector itself. Pile and dust often accumulate in the pockets of clothes, which are densely stamped into the Micro-USB port. This prevents the plug from contacting the contact group closely.
- 🔌 Try charging your phone from another source, such as USB-Computer port or Power Bank.
- 🧹 Carefully inspect the connector in bright light for debris or contact oxidation.
- 🔋 Check the work of the socket by connecting another electrical appliance to it.
Software failures and system freezes
Sometimes the device is fine, but the Android operating system or the MIUI shell freezes in a standby state, the screen can be black, and the indicator can not burn, although the current is coming in, in which case the forced reboot helps.
To do this, you need to press the power button and hold it for a long time. If the system doesn't respond, try a combination of volume and power buttons, which allows you to reset static electricity and restart the control controller.
In some cases, the problem is caused by background processes that consume energy faster than it comes in, especially after updating the firmware or installing heavy applications, and the system may not correctly display the charge level.
☑️ Actions in software freeze
If the phone is turned on after the restart, but charging is slow or jerky, check the list of running applications, close all unnecessary programs and remove the recently installed software that could have caused driver conflict.
Cleaning the connector and eliminating oxidation
The most common technical problem is the oxidation of contacts inside the port. Moisture, sweat and dust create a plaque that prevents the transmission of electricity. For the Redmi 9 with its Micro-USB connector, this is especially true because of the design of the socket.
You can't use metal objects like needles or pins to clean, because you can damage the central plate, and you can use a wooden toothpick or a plastic blade to walk around the inner walls of the connector.
⚠️ Warning: Before cleaning, be sure to turn off the device. The hit of metal shavings on the contacts of the included smartphone is guaranteed to lead to the burning of the board.
If the visual examination shows a greenish coating, you can use a cotton swab slightly soaked in isopropyl alcohol. After processing, allow the port to dry completely for 10-15 minutes before connecting the cable.
- 💨 Blow the connector with compressed air from the electronics canister.
- 🪥 Use a soft dry brush to remove the pile.
- 💧 In case of severe pollution, use a special spray-cleaner contacts.
Why is Micro-USB the problem?
Resetting and calibration of the battery
If the hardware is working, but the phone is acting strangely, the battery may have been calibrated, the system may be 0% and refuse to charge, even though the battery still has power, in which case it requires a full discharge and subsequent charging.
Bring the phone to a full shutdown, then plug it into the grid when it's off. Leave it to charge to 100%, even if the light doesn't light up for long. Once you reach full charge, turn on the device, which will help the controller re-determine the capacity.
In more complex cases, factory resets help. Before this procedure, be sure to save all important data, as it will be deleted. Go to the settings menu and select "Reset settings".
Settings → About the phone → Reset settings → Erase all dataOnce reset, the phone will return to its original state. If the problem was a software conflict of the charging drivers, it should disappear. If the Xiaomi Redmi 9 continues to ignore the charger, it is likely the hardware.
💡
Leave your phone on charge for 3-4 hours, even if the screen is not responding. Sometimes a deep discharge takes a long time to "swing" the battery chemistry.
Hardware malfunctions: battery and plume
When software is exhausted, you have to talk about physical wear. Lithium polymer batteries have a limited resource of charging cycles. Over time, internal resistance increases, and the battery stops taking current.
Another common problem is that the battery plume is moving away from the motherboard, and if the phone fell, the connector could shift, and in this case, you need to disassemble the back cover and reconnect the plume, and be careful, the lid is glued, and you need a hair dryer to remove it.
It's also worth checking the integrity of the plume itself, and it should not have any cracks or heat marks, and if the battery is swelling, it's strictly forbidden to operate the device, which is a fire hazard.
| Symptoms. | Probable cause | Difficulty of repair |
|---|---|---|
| The phone only charges in a certain position. | Broken Micro-USB connector | Medium (needs ration) |
| Charging is going, but the percentage is not growing | Wear of the battery or controller | Low (replacement of the battery) |
| The indicator flashes red. | Deep discharge or error | Low (calibration) |
| Phone's warming up by the connector | Short circuit in the chain | High (toll repairs) |
When is the time to bring your phone to service?
There are a number of signs that self-repairing is useless and dangerous. If you smell burning, hear crackling, or see smoke, immediately disconnect the device from the network. Further attempts to charge can lead to fire.
If the cable, the power supply, and even the battery still have a problem, the motherboard may have malfunctioned, the power controller (IC charging) or other circuit elements may have burned, requiring professional diagnostics and soldering under the microscope.
⚠️ Attempts to solder the power controller without experience and equipment 90% And if you have a phone that's still in water, you can get it to the end of the day, and if you have a phone that's been in the water, and if it's still working, you can start to corrosion after a while, and you'll be able to ultrasonicly clean the board. 🔥 The device heats up strongly at the bottom when connected to charging. 🌊 The smartphone was exposed to moisture or dropped into water. 📉 Battery discharges to 0% post 15-20 minutes of active use. 💡If the phone doesn't charge after replacing the cable, power supply and cleaning the connector, the problem is with probability. 95% It's in the battery or the power controller on the board (FAQ) Why Redmi? 9 It only charges when it is off? This may indicate that running background processes consume more power than the charger gets, and that the battery may wear out when it can't take charge under the load of a running processor. 9 high-load 30W? Xiaomi's current power controllers regulate the current, the phone takes as much as it needs, but using low-quality power units can damage the device. 9 s 0 before 100%? When using a standard charger 10W full cycle is about 2.5 - 3 When using more powerful adapters (18W) time is shortened to 2 The phone can only support the standard speed. 10W, It does not support Quick Charge. 3.0. Phone shows charging, but percentage doesn't increase? Try turning off the phone and charging it in this state. If that doesn't work, it's likely that the battery has lost its capacity and needs to be replaced, or the charge controller on the board has failed.