Help Phone keeps restarting

[uzee]

Hi everyone

My sister has a Note 4 and it has now by random started to restart by itself. She thinks the phone also feels hot.

Any ideas of the cause and/or any solutions?

 

[Hadron]

There are quite a few possibilities, especially if it really is getting hot. Has anything changed in how she uses it, or has she replaced the battery, or has anything happened to it (e.g. it got wet a couple of weeks or even months ago)?

But since the Note 4 has a user-removable battery the first thing I'd do is check that out. Remove it and look for any sign of swelling (phone batteries are generally flat, so if it isn't that's a problem). If the battery has started to swell it needs to be replaced: a swollen battery is a fire hazard.

If the battery seems OK, the question is whether it's getting genuinely hot. If a phone gets too hot it should slow down, which allows it to cool, in order to protect the battery. If it gets really too hot it will crash, shut down or restart, so heating could explain the symptoms. There are apps, such as GSam Battery Monitor, which will keep a record of the temperature and activity - something like that might be useful in identifying the problem.

If it does seem to be getting hot, the important question will be why? This could be a software problem (some rogue app running flat out and heating the phone), or it could be how it's used (but I assume that hasn't changed), or it could be a hardware fault. If it's a motherboard fault then that's unlikely to be economic to repair on an old handset, which is why I suggested checking the battery first.

It's also conceivable that "rogue app" includes a malware infection. These are much less common than many people believe (there are a lot of people whose first response to anything they don't understand is to blame a "virus"), but it's not impossible. So we should consider that possibility as well, though unless she downloads apps from unsafe sources it's more likely that any rogue app is just a bad update (again, if that's the problem in the first place).

Sorry there's no answer there, just the first few things that came to mind.

 

[svim]

Just to add some more suggestions, you should try wiping the system cache partition. The system cache is completely separate from the data partition, where all her files and things reside, so this won't affect any of her saved data. To do this you'll need to restart her Note 4 into its Recovery Mode. While in Recovery Mode it's a text-only interface so you can't use the touch screen, you use the indicated buttons to navigate through the various options. To get into Recovery Mode, power off her Note, and then start it up while simultaneously holding down the Volume Up, the Home, and the Power buttons. Then select the 'wipe cache partition' option and just restart normally again. For a more detailed guide on this:
http://www.hardreset.info/devices/samsung/samsung-n910f-galaxy-note-4/recovery-mode/

You could also try starting up her Note into its Safe Mode. While running in Safe Mode it started up running just Android as is, without any third-party apps pre-loading themselves in the background. If her Note isn't heating up while in Safe Mode that does indicate some app she installed is the culprit. Determining just which one could take some work.
Anyway, here's a nice write-up on Safe Mode for a Note 4:
https://www.androidcentral.com/galaxy-note-4-safe-mode

A more extreme measure is to do a Factory Reset. This will wipe all her data so it's very important to have all her files and things backed up. All files, browser bookmarks, saved WiFi networks, everything. Actually it's really important to have a good, automatic backup solution implemented so matter what anyway.
The point in doing a Factory Reset is to return the phone back to it's original, first-time-use state so I'd do this only as a last resort option. Basically while running the phone in Safe Mode should give you a similar and much less destructive experience since it's just running a 'clean' Android operating system -- the plus being with Safe Mode you just reboot the phone and it's back to the way it was while with a Factory Reset there's an involved restore process you have to go through.

If none of the above make an improvement, you could try flashing a stock ROM. Flashing a ROM is similar to reinstalling the operating system on a computer. It would help to know the exact model I.D. of her Note 4 to give more detailed instructions but just a quick run-down -- you'll need to use a computer to flash the ROM onto your phone; and you'll need to download the required ROM that exactly matches her model and carrier and download the Odin or the Heimdall utility to do the actual flashing.
https://updato.com/firmware-archive-select-model?q=GALAXY+Note+4&exact=1&r=&v=&rpp=100

 

[philayl]

It almost certainly sounds like a failing battery, I would change it as soon as possible with a genuine one. Phil