Hi @Dod0, very sorry to hear about your device. 
After you had performed the factory reset of your device, did you install any applications or restored a backup directly after, or did you use the device without any downloaded applications for 24 hours and you still experienced this behaviour?
In your case, I'd recommend that you perform a software repair using Xperia Companion. This is a bit different from a normal factory reset as it will reinstall the latest available software in your device, just to make sure that the software is not the cause of this behaviour. Do note that in the same process, all data stored on the internal storage will be deleted, so it's advised that you create a backup using Xperia Companion before you start with the repair.
Let me know how it goes!
Jonas thank you so much for replying.
About my device first i did the factory reset it didn't,so i started looking for solution on the Internet there i found the factory reset fix thingy using companion app i did the reset and it worked for about a month regardless the apps i downloaded then it started again.One more thing my phone restarts every 24h with system ui window and mosaic wallpaper but i noticed if i restart the phone before 24h runs out it doesn't crash. Again thank you for replying, hope hearing from you soon 
Hi again!
Oh, I see, thank you for this excellent information, however it does sound very strange.
As you have already performed a software repair, would it be possible for you to have the device rebooted in safe mode for 24 hours in a row without a restart? That way we can see if this is caused by a downloaded application or not.
I understand having your device rebooted in safe mode for an entire day is not the most fun thing to do, but maybe you can try it on a weekend, if you are using your device a bit less on weekends compared to normal days.
Keep me posted!
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