An iPhone usually keeps restarting because of a software problem (a failed update, full storage or a bad app) or a hardware problem (most often a worn battery or a faulty part). Start with a force restart, then update iOS, free up storage and check Battery Health. If it still loops, reinstall iOS in Recovery Mode, and choose Update first so your data stays put.

Why Does My iPhone Keep Restarting?

A restart loop (often called a boot loop) is when your iPhone cycles between a black screen and the Apple logo without ever reaching the Home Screen. A random restart is different: the phone works, then shuts down and reboots without warning.

Both come from the same short list of causes:

• Software: a botched iOS update, corrupted system files, a buggy app or nearly full storage.
• Battery: an old or failing battery that can’t deliver steady power.
• Hardware parts: a faulty charge port, a bad sensor connection or a damaged logic board.
• Liquid damage: even a small amount can cause trouble later.

The logic board is the main circuit board that connects everything inside your iPhone. Almost every signal in the phone passes through it, which is why failures elsewhere can end up looking like random reboots.

Apple’s own advice is simple: make sure your iOS and apps are up to date, then check your battery health. If the battery is fine and the restarts continue, the phone may need service.

The Restart Rhythm Test: Which One Are You?

Most guides hand you a giant list of fixes. A better first move is to notice the pattern. Use a stopwatch or your watch to time the gap between restarts, and match it to this table.

What you see	Most likely cause	Start here
Phone works normally, then restarts about every 3 minutes	A sensor not reporting in	Hardware check, then the panic log
Black screen, Apple logo, black screen, never reaching the Home Screen	Boot loop: failed update, corrupted iOS or hardware	Recovery Mode
Random restarts at unpredictable times	Battery, storage, a bad app or an iOS bug	Free fixes, then Battery Health
Restarts mainly in the cold or at low battery %	A battery struggling to deliver power	Warm up, charge, check the battery
Restarts began right after a repair	A loose connector or low-quality part	Go back to the repairer

Why the 3-minute rhythm matters: iFixit explains that starting with the iPhone X, any sensor on a set list must signal every 180 seconds or the phone restarts as a protective measure. If your phone boots fine but dies at about the three-minute mark, that’s a strong clue that a part isn’t reporting in. Skip ahead to the panic log section below. 

Free Fixes That Work for Most Software Restarts

Work through these in order. Each one is safe and won’t erase your data.

1. Force restart your iPhone

A force restart interrupts the power cycle and clears minor software glitches. The button sequence depends on your model:

• iPhone 8 or later (including SE 2nd and 3rd gen): press and release Volume Up, press and release Volume Down, then hold the Side button until the Apple logo appears.
• iPhone 7 or 7 Plus: hold Volume Down and the Side button together until the Apple logo appears.
• iPhone 6s or earlier: hold the Home button and the Top (or Side) button together until the Apple logo appears.

These are the standard sequences, as laid out in one reply on the Microsoft Community thread. Apple publishes the same steps on its support site. 

2. Try a different charger and cable

Your phone may not be getting enough power to finish booting. iFixit’s first suggestion is to connect to a known working or different charger. Plug in for at least 30 minutes before judging the result. 

3. Update iOS and your apps

If you can keep the phone on long enough, go to Settings > General > Software Update. Then update your apps in the App Store. A bug fixed in a newer iOS version is the cheapest cure there is.

4. Free up storage

A completely full phone has no room to work. iFixit compares it to a sock drawer that can’t close: devices need some free space to operate properly. 

Go to Settings > General > iPhone Storage. Delete large videos, unused apps and old downloads. Back up your photos first.

5. Remove a recently added app

Did the restarts begin after you installed or updated something? Open iPhone Storage, find that app and delete it. Social media apps, VPN apps and third-party keyboards are common suspects, according to a user in the Microsoft thread. Treat that as a lead to a test, not a rule.

How Do I Fix an iPhone Stuck in a Restart Loop?

If your phone never reaches the Home Screen, the settings-based fixes above won’t work. You need a computer.

Recovery Mode: choose Update first

Recovery Mode lets a Mac or PC reinstall iOS even when your phone can’t boot.

• Connect your iPhone to the computer with a cable.
• Open Finder (Mac) or iTunes / Apple Devices (Windows).
• Do the force restart sequence for your model, but keep holding the last button until you see the recovery screen (a computer and cable).
• When the pop-up appears, choose Update, not Restore.

Update reinstalls iOS without erasing your data. If the Update fails, or the loop starts again, go back into Recovery Mode and choose Restore. 

Will I lose my data?

Option	Erases your data?	When to use it
Force restart	No	Always first
iOS update (normal)	No	If the phone stays on long enough
Recovery Mode: Update	No (reinstalls iOS only)	First choice for a boot loop
Recovery Mode: Restore	Yes, everything	If Update fails
DFU restore	Yes, everything	Last software option

Restore erases everything on your iPhone and installs the latest iOS. If you have a recent iCloud or computer backup, you can put your data back afterwards. If you don’t, try every other step first. 

DFU mode: the last software option

DFU (Device Firmware Update) mode goes deeper than Recovery Mode and reinstalls iOS at a lower level. The button sequence is fiddly and differs by model, so follow Apple’s current instructions rather than a forum post.

A useful rule of thumb: a boot loop that survives a DFU restore is almost certainly a hardware problem. That tells you it’s time to stop DIY and book a repair. 

Is It the Battery? How to Check in 30 Seconds

A worn battery is one of the most common hardware causes. You can check it in a few taps, if your phone stays on long enough.

• iPhone 15 and later: go to Settings > Battery > Battery Health. Apple says you can see maximum capacity, whether a replacement is recommended, the cycle count, and the battery’s manufacture and first-use dates. 
• iPhone 11, 12, 13 and 14: go to Settings > Battery > Battery Health & Charging.

Look for the word Service or a maximum capacity below 80%. iFixit notes that under Apple’s guidelines, a capacity below 80% needs battery service. 

Also check for swelling. A battery that is puffing up can lift the screen along one side. If you see that, stop using the phone and get it checked. Swollen lithium-ion batteries can be hazardous.

Read Your iPhone’s Panic Log (Plain English)

When the iPhone restarts itself for a protective reason, it often writes a note called a panic log. Reading it sounds scary, but it takes two minutes.

• Go to Settings > Privacy & Security > Analytics & Improvements > Analytics Data. (The exact label varies slightly between iOS versions.)
• Scroll for entries with panic or panic-full in the name.
• Open the newest one and look for the panic string.
• Look for the words thermalmonitord or watchdog timeout. iFixit says these point to a missing sensor. 

If you find one, the sensor named in the log is your clue. iFixit’s table links sensor names to parts. For example, a barometer fault points to the charge port assembly, while battery-temperature sensors point to the battery or its connector.

You don’t need to fix it yourself. You can hand the panic string to a repair technician and save them diagnostic time.

Restarts That Began After a Screen or Battery Replacement

Did the restarts start soon after a repair? That’s a strong clue. Data-recovery firm SalvageData lists problems that begin immediately after a battery, screen or charging-port replacement as a sign of a hardware cause. 

Two common reasons:

• A loose or damaged connector from the repair.
• A low-quality part. iFixit warns that substandard third-party replacement charge-port parts are rampant. 

Go back to the shop that did the repair and explain the timeline. A good shop will re-check its work.

Quick Liquid Damage Check

Even if your phone seems fine, a small amount of moisture can cause trouble. SalvageData notes that corrosion can develop over hours or days, so a phone that seems to recover after drying may start restarting later. 

To check, eject the SIM tray and shine a flashlight inside. iFixit says the liquid contact indicator is white if dry and red if it has touched liquid. A red sticker isn’t proof of damage, but it’s worth mentioning to a technician. 

And skip the bag of rice. iFixit specifically calls the rice trick a myth.

After an iOS Update

Restarts that start right after an update usually mean the install didn’t finish cleanly. Try these in order:

• Force restart.
• Check Software Update for a newer version.
• Use Recovery Mode and choose Update.

You may also see a post online claiming “iOS X is breaking iPhones.” Be careful with those. For example, one Apple Community user reported an iPhone 15 Pro Max falling into a boot loop around an iOS 26 update. That’s a single user report, not proof of a widespread bug. If many people have the same problem, an Apple fix usually follows quickly.

In Canada: When to Stop DIY and Where to Go

Try the free fixes and Recovery Mode first. Then stop and get help if any of these are true:

• The loop survives a Restore or DFU restore.
• Battery Health says Service, or you see swelling.
• The panic log points to a sensor or part.
• The phone got wet.

Where to go in Canada:

• Apple Store or Apple Authorized Service Provider (AASP): genuine parts and Apple’s official diagnostics. Book through Apple Canada’s support site.
• Independent repair shops: often faster and sometimes cheaper. Ask about the parts they use and the warranty on the repair.

What it may cost: prices vary a lot by model. For one recent example, Apple Canada lists out-of-warranty battery service for the iPhone 18 Pro at $179, up $14 from last year. Older models cost different amounts. Check Apple Canada’s repair page for your exact model before you go. 

The Canadian winter factor: Cold weather makes lithium-ion batteries less able to deliver power. An already tired battery may shut the phone down on a cold commute even when it shows 30% or more. If your restarts happen outside in winter and stop indoors, suspect the battery first. Apple recommends keeping the iPhone in ambient temperatures of about 32° to 95°F (0° to 35°C). 

Conclusion

Match your pattern first. Restarting every ~3 minutes points to a sensor, a loop at the Apple logo points to iOS, and cold-weather shutdowns point to the battery. Then work from safest to riskiest: force restart, update, free storage, Recovery Mode Update, and only then Restore or DFU. If the problem survives a full restore, it’s almost certainly hardware, so book a repair.

FAQs

Why does my iPhone restart every 3 minutes?

This pattern often points to a missing sensor signal. iFixit explains that some iPhones require specific sensors to report in every 180 seconds, or the phone restarts. Check the panic log for “watchdog timeout” or “thermalmonitord,” then ask a technician to inspect the battery, charge port and connectors. 

Will fixing a boot loop erase my data?

Not necessarily. In Recovery Mode, Update reinstalls iOS without erasing your data, and Restore erases everything. Try Update first. If you must Restore, you can reload your data from an iCloud or computer backup afterwards.

Can a bad battery make an iPhone restart?

Yes. A worn or damaged battery can’t supply steady power, so the phone shuts down. Check Settings > Battery > Battery Health. If it says Service or shows under 80%, a replacement is a reasonable first step.

Does low storage cause restarts?

It can. iFixit says devices need some free space to operate properly, and a full phone may struggle to run. Free up space under Settings > General > iPhone Storage. 

Is my restarting iPhone a hardware or software problem?

Try software fixes first: force restart, update, free storage and Recovery Mode. If the problem survives a full Restore or DFU restore, it’s very likely hardware.

How much does it cost to fix a restarting iPhone in Canada?

 It depends on the cause and the model. A battery service is often the cheapest fix. One example is Apple Canada’s listed price of $179 for the iPhone 18 Pro, but other models differ. Get a quote from Apple Canada or an independent shop.