An iPhone that repeatedly shuts down and restarts—exhibiting a black screen, a complete power‑off, and a subsequent reboot that only allows brief operation before the issue recurs—is suffering from a recurring system failure 

Below is a clear, step‑by‑step guide to stop the iPhone restart cycle, from the simplest fix to the most thorough solution.  

Why Does My iPhone Keep Shutting Down and Restarting? 

When your iPhone repeatedly goes black, reboots, works for a few minutes, then crashes again, it’s not a single‑issue problem. The reasons fall into four main categories: software glitches, system update failures, hardware limitations (especially battery), and storage/overheating. Let’s break each down. 

1. iOS System Errors or Failed Updates

2. Battery Problems that iPhone cannot receive enough power during startup.

3. Low iPhone Storage Space leading to crashes and repeated restarts.

4. Problematic Apps can conflict with iOS and trigger random restarts, especially after installing or updating an app.

Situation

Recommended Fix

Occasional restart

Force restart

Boot loop after iOS update

Force restart → Recovery Mode update

Battery capacity below 80%

Replace battery

Want to avoid data loss and manual hassle

Tenorshare ReiBoot Standard Repair

All else has failed

DFU Mode Restore

1. Force Restart – The Quickest First Step

When your iPhone keeps turning off and restarting for no apparent reason, a force restart interrupts the abnormal boot sequence and clears temporary software conflicts. It does not erase any data.

For iPhone 8 and newer (including iPhone 15, iPhone 16, and later models):

  1. Quickly press and release the Volume Up button.
  2. Quickly press and release the Volume Down button.
  3. Press and hold the Side button until the Apple logo appears.
  4. Keep holding for around 10–20 seconds if necessary.

For iPhone 7 / 7 Plus:

  1. Press and hold the Volume Down button.
  2. Press and hold the Side button.
  3. Release when the Apple logo appears.

For iPhone 6s or earlier:

  1. Press and hold the Home button.
  2. Press and hold the Side/Top button.
  3. Release after seeing the Apple logo.

If your iPhone does not restart normally after the first attempt, try again. Some devices require multiple attempts to exit a corrupted startup state.

Note: Force restart is safe and won’t affect your personal files.

2. Check and Update iOS (Especially After an Update)

If your iPhone keeps restarting after an iOS update, the problem often comes from an interrupted installation, insufficient free space, or a corrupted firmware download.

If the phone stays on long enough, go to Settings > General > Software Update and install any available patch release. If you can’t get past the boot loop, you’ll need to use a computer to perform a recovery‑mode update (see Step 4 below).

Note: About 2.7% of users experience boot failures within 48 hours of a major iOS release, but over 80% of those cases are resolved with a standard recovery update.

3. Use Tenorshare ReiBoot for a One‑Click Fix (No Data Loss)

If the recovery‑mode update fails or you find the manual steps too complex, there’s a professional tool that can save you time and worry: Tenorshare ReiBoot.

What is Tenorshare ReiBoot?Tenorshare ReiBoot is a dedicated iOS system repair tool that diagnoses and fixes over 150 iOS issues, including boot loops, Apple logo hangs, and recovery mode stalls.

Why choose ReiBoot?

  • No data loss – The “Standard Repair” mode fixes system problems without erasing personal data.
  • Easy to use – Just three clicks to start the repair.
  • Free version available – The free version can enter/exit recovery mode instantly; the Pro version handles deeper system repairs.

How to use ReiBoot:

  • Download and install ReiBoot on your computer (Windows or Mac).
  • Connect your iPhone via USB.
  • Click “Start Repair” → download the firmware → choose “Standard Repair”.
  • The repair process takes about 10‑15 minutes. Once finished, your iPhone will reboot normally with all data intact

4. Recovery Mode via Computer (Fixes Corrupted System Files)

If force restart and basic checks don’t work, system files are likely damaged. Use a computer to restore the iOS without erasing your data (if you choose “Update”).

What you need: A computer (Windows with iTunes, macOS Catalina or later with Finder) and a USB cable.

Enter Recovery Mode: Connect your iPhone to the computer.

iPhone 8 and newer: Press Volume Up → Volume Down → then hold the Side button until the “Connect to iTunes/Finder” screen appears.

iPhone 7: Press and hold Side + Volume Down; iPhone 6s and earlier: Press and hold Home + Top/Side button.

Once the computer detects the device in recovery mode, choose “Update” (keeps your data) or “Restore” (erases everything). Try “Update” first—it reinstalls iOS while preserving your content.

 Make sure you know your Apple ID and password before restoring, because Activation Lock will be required afterward.

5. Ultimate Solution: DFU Mode Restore

If every method above fails, you can try DFU (Device Firmware Update) mode—a deeper system reinstall than Recovery Mode. In DFU mode, the screen stays black, and the computer will detect an iPhone in recovery state. Choose “Restore” to wipe and reinstall iOS completely.

DFU erases all data—so only use this as a last resort, and only if you have a backup (iCloud or computer).

Final Words

From when the iPhone keeps shutting down and restarting to a fully functional device, the journey usually ends with a simple force restart or a recovery‑mode update. If problems persist, Tenorshare ReiBoot offers a safe, data-preserving path that’s far simpler than manual troubleshooting. Try these solutions step by step, and your iPhone should be back to normal in no time.