Turn on airplane mode might fis S4 reboots during backup
I don't know if this will help anyone, but I wanted to share this in case it does.
My S4 (i337) started to have wifi and Bluetooth problems today - trying to turn on either one allowed the slide switch to slide to the right (on), but it stays grey in color for 10-15 seconds, then slides back to the left (off) position without ever turning green. I also ONCE noticed a pop-up toast message appear saying something like "security does allow connection..", but it was too fast to take a screen shot and it never appeared again not matter how many times I tried turning on wifi.
So, what does this have to do with flash fire? I use flashfire to do "normal" backups and it works flawlessly on my S4 (I was able to do a restore and cloned a phone). But I have to use version 0.53 for it to work correctly on my 5.0.1 S4.
I then tried to do a backup today so I can restore it on another S4 to see if the problem follows the backup (software issue) or doesn't (hardware with first/current phone). But Flashfire kept rebooting the phone randomly during the [system] part of the backup, just like other S4 users have reported, but that I never experience before today. I tried this four times and it always rebooted during the backup.
On a hunch that this might be related to the wifi/Bluetooth radio, I set my phone into airplane mode (disables wifi and Bluetooth), and sure enough, the flashfire backup then completed successfully!
So, if you have an S4 and it keep rebooting when you try doing a backup, try installing version 0.53 and also turn on airplane mode and see if that works for you.