Electronics can fail you at any given time. Murphy’s Law might be watching your situation very closely 
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/e/ has Rooted debugging available in the Developer options. This is not rooting the phone. This gives ADB the possibility to run as root on the phone, which e.g. would give it access to the whole data partition. This might be a way to backup more than what is usually possible … [HOWTO] Backup and Restore Data on Android Devices - #36 by petefoth.