Why a phone suddenly starts acting on its own

It shuts down in the middle of a call. It reboots while you're playing a game. It restarts at night—you can tell because all your notifications are gone. Such phones appear in our workshop regularly, and the first thing a client wants to know is: is the battery dying, or is there something wrong with the firmware?

The answer isn't always obvious. Both options produce similar symptoms but are treated differently. Let's break it down one by one.

Common causes of spontaneous reboots

Battery

The most common cause, especially for phones older than two years. The battery degrades, loses capacity, and stops holding a stable voltage under load. The system experiences a power drop and interprets this as a signal to reboot.

Signs that point to the battery include:

  • the phone reboots specifically under load—during navigation, a call, or a game;
  • the charge level "jumps": it was just at 40%, and suddenly it's at 5% or shuts down entirely;
  • the casing near the battery is slightly swollen;
  • the problem intensifies significantly in cold weather.

There was a case: a client brought in a Samsung Galaxy A52—the phone would shut down at 30–35% charge. It looked fine from the outside. We opened it up—the battery was swollen, and its capacity had dropped to 58% of its nominal value. We replaced the battery for about 1,800 rubles, and the problem was gone that same day.

Firmware and software

The second most frequent culprit is a software glitch. A buggy system update, a conflict with a third-party app, full storage, or a virus. All of these can lead to chaotic reboots.

Software causes are suggested by the following:

  • reboots started after an Android update or installing a new app;
  • the phone freezes on the loading screen and cannot start properly;
  • the settings show that the storage is almost completely full;
  • the reboot always happens in the same app.

Hardware issues

Less common, but it happens: oxidation of contacts after moisture exposure, a damaged ribbon cable, or board issues due to overheating or impact. You cannot solve this on your own.

What you can try yourself

  1. Check the battery status. On Android 12 and newer—"Settings" → "Battery" → "Battery health". If it's below 80%, it's time to replace it.
  2. Delete recently installed apps or those after which the problem began.
  3. Clear the cache. In the settings for each suspicious app, tap "Clear cache".
  4. Update the firmware—the manufacturer might have already released a patch specifically for this error.
  5. Factory reset. A last resort, but it often helps. Just make sure to back up your data first: photos, contacts, and messages.

If the reboots stop after a reset, the problem was software-related. If not, it's a hardware issue.

When you can't do without a technician

Self-help methods are good up to a certain point. Come see us if:

  • you've tried everything, but the phone continues to reboot;
  • the device reboots even while charging—this is a warning sign;
  • the battery is swollen—it is unsafe to continue using it;
  • the phone was recently exposed to water or suffered a heavy drop.

Recently, a client came in with a Xiaomi Redmi Note 11—it was rebooting several times a day. They had already performed a reset themselves, but it didn't help. During diagnostics, we found oxidation under the battery—a consequence of old water damage. We cleaned it and replaced the battery. The phone has been working fine for several months now.

If your Android is behaving unpredictably and you've already tried everything you could, come to iClub at 35 Kommunisticheskaya Street. Diagnostics are free; we'll tell you honestly what happened and what needs to be done.