Stuck on the logo: what a boot loop actually is
The short answer
A boot loop is the device failing partway through starting and trying again. The cause is usually software, sometimes storage, occasionally a battery that cannot deliver enough current, and rarely the board. What happened just before it started is the single most useful clue.
What is happening between the button and the home screen
Powering on runs a sequence: the board brings up power rails in order, checks the low-level firmware, hands off to the operating system, mounts the storage, and starts the interface. A failure at any point in that chain either freezes or restarts.
Where it stops tells you a lot. A device that never shows a logo has failed early, usually in power. One that shows a logo and hangs has got as far as the operating system. One that loops has got far enough to fail and try again.
That is why the free diagnostic measures current draw rather than just watching the screen: the board's behaviour says which stage it reached, and the screen only shows the last one it managed.
The causes, most likely first
| Cause | Clue | Odds |
|---|---|---|
| A failed or interrupted update | It started during or right after one | Usually recoverable, often without data loss |
| Full storage | It had been warning for weeks | Usually recoverable |
| Corrupt system files | No obvious trigger, gets progressively worse | Often recoverable, sometimes needs a restore |
| A failing battery | An older phone, and it loops harder when cold | Cheap to test, cheap to fix |
| Storage failure | Was slow and freezing before it looped | Data recovery territory |
| Liquid corrosion | It got wet at some point, possibly weeks ago | Depends entirely on how long |
| Board fault | It was dropped, or it gets hot while looping | Diagnostic, then a decision |
What not to do
- Do not keep restarting it. Every attempt on failing hardware is another chance for it to get worse
- Do not factory reset to fix it. That destroys exactly what most people came to recover
- Do not charge it if it has been wet. That is a different problem and charging makes it permanent
- Do not leave it looping. If it is hot and cycling, power it down and let it sit
- Do not follow a video that involves opening it, unless losing the data is fine
What we do
Ask what happened just before, because an update, a drop and a spill lead to three different first moves.
Measure how it behaves electrically, which separates a battery that cannot hold voltage under load from a board that is failing.
Try to reach a recovery state, which distinguishes a software problem from a hardware one before anything is replaced.
And ask, before starting, whether the data or the device is the priority. On a boot loop those are sometimes different routes and the wrong order can cost you both.
Common questions.
It has failed partway through starting. The most common cause by a distance is a failed or interrupted update, which is usually recoverable. Storage, a failing battery and liquid corrosion account for most of the rest.
No. Every attempt on hardware that is failing is another chance for it to get worse, and it does not improve the odds. Leave it off and bring it in.
Not necessarily, and it is the first thing to tell us if it matters. Some routes preserve everything and some do not, and knowing your priority decides which we try first.
Sometimes, and it destroys everything on the device doing it. Never do that as a first step if there is anything on the phone you want.
Yes, and it is the cheapest of the possible causes. A cell that cannot deliver peak current makes the device fail partway through starting, especially when cold.
Where this leads.
Something actually broken? Bring it in.
Free diagnostic, a firm price before any work, and a 360-day warranty on every completed repair.
Book a repair 24/7 · No fix, no fee · 360-day warranty · Free diagnostic