Huawei P9 Keeps Restarting: Fixes That Work

If your Huawei P9 is stuck in a restart loop, the fix is usually a forced restart, clearing the cache partition, or a factory reset. This guide walks you through each step in order, from the least disruptive to the most thorough, so you can get your phone stable again.

Why the Huawei P9 Restarts by Itself

The P9, released in 2016, runs on a Kirin 955 processor and originally shipped with Android 6. Over time, a few common causes trigger the restart loop:

• Software glitch after an update – A failed or interrupted system update can corrupt system files.
• Battery or charging issue – A worn battery or a faulty charger can cause voltage drops that force a reboot.
• Third-party app conflict – An app that misbehaves after an update can crash the system repeatedly.
• Storage nearly full – When internal storage is below a few hundred MB, the system may fail to write temporary files and reboot.
• Hardware damage – A drop or water exposure can loosen internal connections, especially around the battery.

Because the causes vary, you should try fixes in order of simplicity and risk.

First: Force Restart the Phone

A force restart clears temporary memory and often stops a one-off reboot loop. It does not delete your data.

1. Press and hold the power button for 10–15 seconds until the screen goes black.
2. Keep holding until the Huawei logo appears and the phone boots normally.
3. If it boots, check for pending system updates and install them while connected to Wi-Fi.

If the phone reboots again within minutes, move to the next step.

Boot Into Safe Mode to Test Apps

Safe mode disables all third-party apps. If the phone stops restarting in safe mode, an app is the culprit.

1. Turn off the phone.
2. Press and hold the power button until the Huawei logo appears.
3. As soon as the logo shows, press and hold the volume down button.
4. Release when you see “Safe mode” in the bottom-left corner.

In safe mode, use the phone normally for a few hours. If it doesn’t restart, uninstall recently added apps one by one, starting with the most recent. Reboot normally after each uninstall to test.

Clear the Cache Partition

The cache partition stores temporary system files. If these become corrupted, the phone can loop. Clearing it is safe and does not erase personal data.

1. Turn off the phone completely.
2. Press and hold volume up and power together until the Huawei logo appears, then release.
3. Use the volume keys to highlight Wipe cache partition and press the power button to select.
4. Confirm with Yes and wait for the process to finish.
5. Select Reboot system now.

If you don’t see this menu, try volume down instead of volume up. The exact key combo varies slightly by firmware version.

Check Battery Health and Charger

A failing battery is a leading cause of random reboots on aging phones. The P9’s battery is non-removable, so you can’t swap it yourself without tools, but you can test the charger and cable first.

• Use a different, known-good charger and cable. A worn cable can cause voltage drops that trigger reboots.
• Check the charging port for lint or debris with a wooden toothpick (never metal).
• If the phone only restarts when charging, the battery or charging IC may be failing.
• If the phone is over 3–4 years old and reboots under load (e.g., using the camera), the battery likely needs replacement by a technician.

Backup and Factory Reset

If nothing above works, a factory reset will clear all system corruption and return the phone to its out-of-box state. This erases all data, so back up first.

1. Go to Settings > Advanced settings > Backup & reset.
2. Select Backup and save to a microSD card or Huawei cloud if available.
3. Then select Factory data reset and confirm.
4. If the phone won’t boot normally, use the recovery menu from the cache-clearing step and choose Wipe data/factory reset.

After reset, set up the phone as new first. If it stays stable, restore your apps gradually. If it still reboots after a factory reset, the issue is likely hardware.

When to Seek Professional Repair

If a factory reset doesn’t fix the loop, the problem is almost certainly hardware. Common culprits include:

• Battery – swollen, aged, or unable to hold charge.
• Power IC – a chip that manages power delivery can fail and cause random resets.
• Motherboard – a cracked solder joint or water damage.

Get a diagnostic from a reputable phone repair shop. Replacing the battery is often the cheapest fix and may solve the issue. Replacing the motherboard is usually not economical for a phone this old.

Frequently Asked Questions

Will a factory reset delete my photos?

Yes, a factory reset wipes everything on the internal storage, including photos, contacts, and messages. Back up to a microSD card, computer, or cloud before resetting. If you can’t boot the phone, a technician may be able to recover data before resetting.

Why does my P9 restart when I open the camera?

This usually points to a battery that can’t supply enough current under load. The camera draws significant power, and an aging battery may drop voltage and trigger a reboot. Replacing the battery is the typical fix.

Can a bad SD card cause restarts?

Yes, a corrupted or failing microSD card can cause system crashes on some devices. Remove the card and see if the reboots stop. If they do, reformat the card on a computer or replace it.

How do I know if it’s a software or hardware problem?

If the phone reboots in safe mode and after a factory reset, it’s hardware. If it only reboots with certain apps or after an update, it’s software. The forced restart and cache wipe steps also help distinguish the two.

Is there any way to prevent future restart loops?

Keep the phone updated, avoid filling storage past 90%, use original or quality chargers, and replace the battery every 2–3 years. Also, uninstall apps you don’t use, as some background apps can cause conflicts.

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