How To Restart Galaxy Z Flip 4 (2026 Guide)
The Galaxy Z Flip 4 can be restarted using the Side button and Volume Down key, the Quick Settings power menu, or a scheduled auto-restart through Device Care. If your phone is frozen and won’t respond to touch, a force restart using the hardware buttons will get it working again without losing any data.
This guide covers every restart method available on the Z Flip 4 running One UI 6.1 (Android 14), plus how to enter Safe Mode and Recovery Mode for deeper troubleshooting.
Galaxy Z Flip 4 Key Specifications
| Spec | Detail |
|---|---|
| Display | 6.7-inch FHD+ Dynamic AMOLED 2X (2640 × 1080), 120Hz |
| Cover Screen | 1.9-inch Super AMOLED (260 × 512) |
| Processor | Qualcomm Snapdragon 8+ Gen 1 |
| RAM | 8 GB |
| Storage | 128 GB / 256 GB / 512 GB (UFS 3.1) |
| Battery | 3,700 mAh (dual cell), 25W wired, 15W wireless, 4.5W reverse wireless |
| Dimensions (folded) | 71.9 × 84.9 × 15.9–17.1 mm |
| Dimensions (unfolded) | 71.9 × 165.2 × 6.9 mm |
| Weight | 187 g |
| Water Resistance | IPX8 |
| OS (current) | One UI 6.1 based on Android 14 |
How to Restart the Galaxy Z Flip 4
Method 1: Using the Hardware Buttons
This is the fastest way to restart your Z Flip 4.
- Press and hold the Side button and the Volume Down button at the same time for about 2 seconds.
- The power menu appears on screen with three options: Power off, Restart, and Emergency mode.
- Tap Restart.
- Your phone will shut down and reboot automatically. The process takes about 30–45 seconds.
Why Volume Down? Samsung reassigned the Side button (the physical key on the right side of the phone) to launch Bixby by default. A long press of just the Side button opens Bixby instead of the power menu. You can change this behavior in Settings → Advanced features → Side button → Press and hold → Power off menu, which restores the traditional long-press-for-power behavior.
Method 2: From the Quick Settings Panel
If you prefer not to use hardware buttons:
- Swipe down from the top of the screen twice to fully expand the Quick Settings panel.
- Tap the Power icon in the upper-right corner of the panel (it looks like a circle with a vertical line at the top).
- Tap Restart from the power menu.
Method 3: Using Bixby Voice
If your screen is responsive but you can’t easily reach the buttons (for example, if the phone is mounted or in a stand):
- Say “Hi Bixby” or press and hold the Side button to launch Bixby.
- Say “Restart my phone.”
- Confirm when prompted.
This requires Bixby voice wake-up to be enabled in Settings → Advanced features → Bixby → Voice wake-up.
How to Force Restart a Frozen Galaxy Z Flip 4
If your Z Flip 4 is completely frozen — the screen won’t respond to touch, buttons don’t bring up the power menu, or the display is stuck on a black screen — a force restart is the fix. This does not erase any data.
- Press and hold the Side button and the Volume Down button simultaneously.
- Keep holding both buttons for 7–10 seconds. Do not release when the screen goes black.
- The Samsung logo will appear. Release both buttons when you see it.
- The phone will boot up normally.
If the phone still won’t respond after the force restart, make sure it’s not a dead battery. Connect the charger and wait at least 15 minutes before trying the force restart again. The Z Flip 4 won’t show any charging indicator until the battery reaches a minimum threshold.
Common causes of freezing on the Z Flip 4:
- A resource-heavy app (games, video editors) consuming all available RAM
- A One UI software update that didn’t install cleanly — interrupted updates can leave the system in a partially updated state
- Overheating, which triggers thermal throttling and can lock the display
- A third-party launcher or theme that conflicts with One UI’s foldable display handling
How to Set Up Automatic Restart
Samsung’s One UI includes an auto-restart feature in Device Care that periodically reboots the phone to clear cached data and free up memory. This is useful if your Z Flip 4 tends to slow down after several days of use.
Restart When Needed (Automatic)
- Open Settings.
- Tap Battery and device care.
- Tap Auto optimization.
- Toggle on Restart when needed.
With this enabled, Samsung determines the optimal time to restart based on usage patterns. The phone will only restart when the screen is off, the phone is idle, and the battery is above 30%.
Restart on Schedule (Manual Schedule)
- Open Settings.
- Tap Battery and device care.
- Tap Auto optimization.
- Tap Restart on schedule and toggle it on.
- Set your preferred day(s) and time.
The phone will restart within one hour of the scheduled time, but only if these conditions are all met: the screen must be off, the phone must not be in active use, the battery must be above 30%, and SIM card lock must be disabled.
Tip: Setting a weekly restart (for example, every Sunday at 3:00 AM) can help keep your Z Flip 4 running smoothly without you having to think about it.
Note: In One UI 5.0, Samsung temporarily removed the scheduled restart option and replaced it with “Restart when needed” only. The scheduling feature was restored in One UI 6.0 (Android 14). If you don’t see the schedule option, make sure your phone is updated to the latest firmware via Settings → Software update → Download and install.
How to Boot Into Safe Mode
Safe Mode disables all third-party apps and runs only Samsung’s built-in system software. This is the best way to determine whether a downloaded app is causing crashes, freezing, or random reboots.
Enter Safe Mode (Phone is Responsive)
- Press and hold the Side button and Volume Down button together to open the power menu.
- Tap and hold the Power off option for about 2 seconds.
- A Safe mode prompt appears. Tap Safe mode to confirm.
- The phone will restart. You’ll see “Safe mode” in the bottom-left corner of the screen.
Enter Safe Mode (Phone is Off or Frozen)
- Force restart the phone by holding the Side button and Volume Down button for 7–10 seconds.
- As soon as the Samsung logo appears, release both buttons, then immediately press and hold the Volume Down button only.
- Keep holding Volume Down until the phone finishes booting. “Safe mode” will appear at the bottom-left corner.
Exit Safe Mode
Restart the phone normally (Side button + Volume Down → Restart). The phone will boot back into regular mode with all apps re-enabled.
What to do in Safe Mode: If the phone runs normally in Safe Mode (no freezing, no random reboots), a third-party app is the culprit. Start by uninstalling the most recently downloaded apps, then exit Safe Mode and check if the problem returns.
How to Boot Into Recovery Mode
Recovery Mode gives you access to system-level options like wiping the cache partition and performing a factory reset. You should only use this if normal troubleshooting hasn’t resolved the issue.
- Power off the phone completely (Side button + Volume Down → Power off).
- Once the screen goes fully black, press and hold the Volume Up button and the Side button at the same time.
- When the Samsung logo appears, release the Side button but keep holding Volume Up.
- The Android Recovery menu will appear. Use the Volume buttons to navigate and the Side button to select.
Recovery Mode Options
| Option | What It Does |
|---|---|
| Reboot system now | Restarts the phone normally |
| Wipe cache partition | Clears temporary system cache files without deleting personal data — try this first |
| Wipe data/factory reset | Erases all data and resets the phone to factory settings — use as a last resort |
Wipe cache partition is the safest option here. It clears old cached data that can cause slowdowns and glitches after software updates, and it does not delete any of your photos, apps, or personal files.
Troubleshooting: Galaxy Z Flip 4 Keeps Restarting on Its Own
If your Z Flip 4 is rebooting randomly without you initiating a restart, here’s how to diagnose and fix it, starting with the most common causes.
1. Disable Auto Optimization
Samsung’s “Restart when needed” feature in Auto Optimization can trigger unexpected reboots. Turn it off to rule it out:
Settings → Battery and device care → Auto optimization → Toggle off “Restart when needed”
2. Boot Into Safe Mode
Follow the Safe Mode steps above. If the random reboots stop in Safe Mode, a third-party app is causing the problem. Uninstall recently installed apps one at a time until the issue resolves.
3. Check for Software Updates
Buggy firmware can cause reboot loops. Several Z Flip 4 owners on Samsung Community forums reported random reboots after specific One UI updates. Make sure you’re on the latest available version:
Settings → Software update → Download and install
4. Wipe the Cache Partition
Boot into Recovery Mode (instructions above) and select Wipe cache partition. This clears corrupted temporary files without affecting your data.
5. Check Battery Health
A degraded battery that can’t deliver consistent power will cause random shutdowns and reboots. As of 2026, the Z Flip 4’s battery is approaching 3–4 years old depending on your purchase date. Check battery health:
Settings → Battery and device care → Battery → Tap the three-dot menu → Battery usage → Check battery condition
If the battery shows “degraded” or capacity has dropped significantly, a battery replacement is the fix. Samsung charges approximately $99 for a Z Flip 4 battery replacement through their authorized service centers.
6. Factory Reset (Last Resort)
If nothing else works, a factory reset will eliminate any software-based cause. Back up your data first — this erases everything.
- Go to Settings → General management → Reset → Factory data reset.
- Tap Reset and confirm.
Alternatively, if the phone is stuck in a reboot loop and you can’t reach Settings, perform the reset from Recovery Mode (Volume Up + Side button while powered off → select Wipe data/factory reset).
7. Contact Samsung Support
If factory reset doesn’t stop the random reboots, the issue is likely hardware-related (damaged battery, loose flex cable, or motherboard fault). Contact Samsung:
- Phone: 1-800-726-7864
- Website: samsung.com/us/support
- Samsung Members app: Open the app → tap the headset icon for live support
- Walk-in: Find a Samsung-authorized repair center via the Samsung website
Samsung offered four years of security updates for the Z Flip 4 from its August 2022 launch, with the last guaranteed update in August 2026. If your device is still within warranty (one year standard, or extended via Samsung Care+), repairs may be covered.
Recommended Accessories
If your Z Flip 4’s battery is degrading and you need a reliable charging solution, here are some options:
- Samsung 25W Super Fast Charger on Amazon — Official Samsung 25W wall charger with USB-C cable, matches the Z Flip 4’s maximum wired charging speed
- Anker 313 Wireless Charging Pad on Amazon — Budget-friendly Qi wireless charger, compatible with the Z Flip 4’s 15W wireless charging
- Samsung Silicone Cover with Ring for Galaxy Z Flip 4 on Amazon — Slim protective case with a built-in ring for secure grip when the phone is unfolded
Note: Amazon links should be verified before publishing, as product availability and pricing may change.