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andy1

My Z Ultra was all good untill few days ago it suddenly shut of and reboot itself, not once but one after another. Although its not frequent but I can never expect when will the phone reboots again. I've tried resetting and ran the device in safe mode and it even rebooted in safe mode, this problem still occurs after I did a pc companion repair. Please help me out here!

toothpaste

try it for a day or two WITHOUT sim card and WITHOUT sd card

yes, it is very annoying, but i suggest you try it.

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Hampus

Hi,

Perhaps it can be related to your SIM and/or SD-card. If you are using an SD-card, could you try to use it without the SD-card for some days to see if same thing occurs? Regarding the SIM-card, you can try another SIM-card or order a new SIM from your network provider.

toothpaste

if the sim has problems, shouldn't the system notify of the failure and also fail gracefully, instead of randomly rebooting?

andy1

In terms of faulty sim card, could it be the phone not detecting the sim card causing the phone to reboot by itself? I have taken my sim and sd card out and will see how it goes.

toothpaste

if the phone fails to communicate with the sim card, it generally loses signal and says something along the lines of "emergency calls only"

the phone rebooting or hanging means something is very wrong.

i suspect something has to do with a watchdog timer, but still, it shouldn't be rebooting the phone without any kind of warning or

if it is rooted you can do a dmesg, or leave a script running (locally or via adb) to collect dmesg and/or other log data and maybe see if something pops up in there.

Hampus

If the SIM-card is removed or loses its connection, the phone should display the message "SIM card removed, restarting" and then the phone will restart. So a faulty SIM-card, can cause this behaviour.

andy1

I also forgot to mention that if I want to perform normal shut off, after a random reboot, the phone will just go to a black screen but not completely shut off and it didnt even vibrate, I can still see the panel lit, then the phone goes completely black and after a few seconds it reboots itself up!

andy1

Yeah my phone never showed it, it.just went bam! Shutoff and reboot. No its not rooted.

toothpaste

That behavior is kinda unwanted.

I can't imagine my pc **bleep** its pants and rebooting without any warning or option to delay it, just because i removed a wifi dongle, or just because the ethernet cable came loose...