Xiaomi Redmi Note 4 (mido and nikel models) is one of the brand’s most popular devices, but even it is not immune to breakdowns: a situation where the battery is completely discharged, swelled or physically absent, and the phone needs to be turned on urgently, is familiar to many repairmen and owners. Turning on a smartphone without a battery is technically possible, but requires strict adherence to the connection schemes and understanding of the risks.
In this article, we will discuss three working methods for launching the Redmi Note 4 without a battery: through a modified version of the device. USB-The cable, direct power from the unit and activation of test points on the board, each method has its own nuances, from the need for soldering to the risk of damage to the power controller. If you do not have experience with electronics, it is better to consult a specialist.
Before you start, check if the battery is really a problem. Sometimes the smartphone doesn't turn on because:
- 🔌 Damaged Micro-USB connector (oxidation, contact break);
- 🔋 Faulty charging controller (PMIC);
- 🛠️ Short circuit on the board (often after falling or getting moisture).
Method 1: Nutrition through modified USB-cable
The most affordable way is to apply the voltage directly via USB, bypassing the battery, and this will require a cable with soldered wires to the contacts of the battery on the smartphone board.
Step-by-step:
- Disassemble the Redmi Note 4 by removing the back cover and disconnecting the battery (if it is, but defective).
- Find the battery contacts on the board - usually two large pads labeled B+ (plus) and B- (minus).
- Take it. USB-cable (preferably with thick wires) and clean the red (+5V) black (GND) wire.
- Softed red wire to B+, black wire to B-. Don't confuse polarity!
- Connect the cable to the charger (it is better to use the unit on 5V/2A).
Prepared USB-bare-wire|Stolen iron and solder|Multimeter for voltage testing|Charger 5V/2A|Screwdriver for disassembling the phone
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If done correctly, the smartphone should vibrate and show the Mi logo. If the screen remains black:
- 🔍 Check the quality of the soldering (possible bad contact);
- 📉 Make sure that the voltage on the contacts is 4.2–4.4V (multimeter);
- 🚫 Possibly damaged power controller (PMIC).
⚠️ Note: Do not use power supplies with a voltage higher 5V — It's going to burn the board, and avoid cheap, thin wire cables, because they can overheat.
2. Method 2: Direct connection to the power supply
A more reliable but technically sophisticated way is to supply power from a lab power supply or a modified voltage-adjusted charger, a method often used in service centers.
Equipment required:
- 🔧 Laboratory power supply (or charging with adjustment 3.7–4.4V);
- 🔌 Crocodile wires for connection;
- 📊 Multimeter for current control.
Algorithm of action:
- Disconnect the battery and find the B+ and B- contacts on the board.
- Connect the "crocodiles" to the power supply: red - to +, black - to -.
- Set the voltage on the block in the range of 3.8-4.2V (the initial value is 3.8V).
- Limit the current to 0.5A to avoid overheating.
- Connect the wires to the board and gradually increase the voltage to 4.2V.
| Voltage (V) | Current (A) | Smartphone reaction | Action |
|---|---|---|---|
| 3.7–3.8 | 0.1–0.3 | No reaction. | Check the contacts, increase the current to 0.5A |
| 4.0–4.1 | 0.3–0.5 | Vibration, Mi logo | Hold on for 10-15 seconds. |
| 4.2–4.4 | 0.5–1.0 | Booting the system | Don't go over 4.4V! |
| >4.5 | Anybody. | Risk of damage to the fee | Shut it off immediately! |
A critical novice error is to connect a 5V power supply directly to the battery contacts, guaranteed to burn the power controller (PMIC) and require costly repairs.
Laboratory unit|Adjustable charger|USB-voltmeter|None of the above.-->
3. Method 3: Activation of test points (Test Points)
If the first two methods failed, the reason could be a power controller lock, in which case the activation of Test Points, the special contacts on the board that force the device to start, helps.
For the Xiaomi Redmi Note 4 (mido), the test points are located next to the battery connector.
- 🔘 TP1 — usually marked CLK;
- 🔘 TP2 — may be signed as DATA.
Instructions:
- Unplug the battery and find test points (see the photo board below).
- Close TP1 and TP2 with tweezers or a screwdriver for 5-10 seconds.
- Connect the modified one. USB-cable (as in Method 1) or power supply.
- If the smartphone does not respond, repeat the circuit, holding the contacts longer.
Where are the test points on the Redmi Note 4?
⚠️ Warning: Do not close the test points with metal objects without insulation - this can cause a short circuit. Use a plastic tweezer handle or a wooden stick wrapped in foil.
Possible problems and solutions
Even with the right connection, the Redmi Note 4 may not turn on. Let’s consider the typical errors and how to fix them:
| Problem. | Probable cause | Decision |
|---|---|---|
| The phone vibrates but does not load. | The loader or firmware is damaged. | Fastboot or EDL to your device |
| The screen is black, there is no vibration. | Short circuit on board | Check the charge for damage (blackened elements, bloated capacitors) |
| The phone turns on, but immediately turns off. | Insufficient voltage or current | Increase voltage to 4.2V or increase current to 1A |
| Heated USB connector or board | Current overload or CZ | Turn off the power immediately, check rations and contacts. |
After successful activation, the smartphone does not determine SIM-The card or not charged, the problem may be:
- 📶 A damaged slot. SIM (Check the contacts);
- 🔋 Faulty charging controller (PMIC or BQ24193);
- 📱 Firmware failure (requires flashing through Mi Flash Tool).
💡
If the phone is unstable after turning on without a battery (reboots itself, brakes), try connecting it to a known battery for 5-10 minutes.
5. Alternative methods (for experienced users)
If standard methods don't work, you can try more radical approaches, which require special equipment and skills.
- 🔧 Firmware through EDL (Emergency Download Mode: If the phone doesn’t turn on even with power, it can be “resuscitated” via mode EDL. That's what Qualcomm needs. HS-USB QDLoader 9008 driver and Mi Flash Tool. Connect your phone to your PC by holding the Volume Down button + Power, and stitch the stock firmware.
- 🔌 Use of donor board: If the power controller is burned, you can temporarily connect a working battery from another Redmi Note 4 (even discharged) and try to turn on the device.
- 🛠️ Replacement PMIC: If all attempts to turn on a phone without a battery lead to a short circuit, most likely the power controller is faulty (PMIC). Replacement requires experience with a soldering station and BGA-equipment.
⚠️ Attention: Firmware through EDL It will reset all data on the phone, including the associated Mi Account. If the device was blocked, after the firmware may need to unlock the bootloader.
6.When to contact the service center
Not all breakdowns can be repaired by yourself.
- 🔥 On the board, traces of burns or melted elements are visible;
- 💧 The phone was in contact with the liquid (even if everything was dry on the outside);
- 🔧 You are not sure about your soldering or electronics skills;
- 📵 The phone is turned on but does not define the network or modules (camera, speaker).
The cost of repairing Xiaomi Redmi Note 4 in the service:
| Type of repair | Cost (rupe) | Timeline |
|---|---|---|
| Diagnostics | 500–1000 | 15-30 minutes |
| Battery replacement | 1500–2500 | 1-2 hours |
| Power Controller Repair (PMIC) | 3000–6000 | 1-3 days |
| Firmware through EDL | 1000–2000 | 1 hour |
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If the phone doesn’t turn on even after all the manipulations, don’t try to “resuscitate” it with artisanal methods (such as heating in the oven or applying high voltage), which will lead to irreversible damage and increase the cost of repair.