I bought a used Galaxy S7 about a month ago. Ever since I bought it, it has had a tendency to reboot fairly unpredictably for no obvious reason. I've noticed that if I am using a particular app when it reboots, it will usually reboot again if I attempt to use that app soon after startup.

Currently the phone is locked in a cycle of rebooting within a minute of startup regardless of what I do (including booting in Safe Mode). It has rebooted at least 20 times in this way, with uptime always or almost always under 1 minute before reboot and no interaction with the phone at all.

I've tried clearing the Dalvik cache and other cache partition; although this did not fix the issue, I did notice that it took quite a bit longer (multiple minutes) to reboot on the first bootup after clearing the caches.

How can I get my phone to stabilize and hopefully avoid future unsolicited reboots?

UPDATE: whoops, forgot to read that info link for [boot-loop]. Apparently at this point I'm expected to give up and do a factory reset. However, I'm concerned that the issue may be that there are bad blocks in the NAND. Is this a possibility, and if so, is there a way to mark them so the firmware does not attempt to use them?

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    Random reboots could be due to almost any software/hardware related issue. Usually a kernel panic log (like in pstore, if you can access) can give a quick hint what happened just before reboot. Property persist.sys.boot.reason may also give a tiny hint in some situations. If a factory reset or firmware update doesn't fix it, most probably it's hardware related e.g. RAM or some thermal problem. Contacting official CS will be more beneficial in that case. – Irfan Latif Jul 5 '19 at 15:35
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    A dying eMMC usually doesn't cause random reboots (AFA I've experienced and observed), it starts with write-protection of memory, so the data gets lost and you will face funny situations. Then some partition may fail. A factory reset will give you better clue on that e.g. if you fail to wipe /data or /cache. Use blkdiscard tool to make sure memory is completely erased, but that requires root. Bad silicon cells of flash memory are fully handled by eMMC firmware, you have no control over them, even on costly SSDs. And phones even don't have S.M.A.R.T to know about eMMC's life beforehand. – Irfan Latif Jul 5 '19 at 15:43
  • Sorry, how would I access pstore? I'm in the recovery shell but I don't see it in /dev or /sys/fs – intuited Jul 6 '19 at 17:18
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    Then your kernel (main or in recovery or both) isn't built with CONFIG_PSTORE. Do grep pstore /proc/filesystems to confirm. – Irfan Latif Jul 6 '19 at 17:28

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